/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.lang3.builder;
  
  import java.lang.reflect.AccessibleObject;
  import java.lang.reflect.Field;
  import java.lang.reflect.Modifier;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  
  import org.apache.commons.lang3.ArrayUtils;
  import org.apache.commons.lang3.ClassUtils;
  import org.apache.commons.lang3.tuple.Pair;
  
  /**
   * Assists in implementing {@link Object#equals(Object)} methods.
   *
   * <p>This class provides methods to build a good equals method for any
   * class. It follows rules laid out in
   * <a href="https://www.oracle.com/java/technologies/effectivejava.html">Effective Java</a>
   * , by Joshua Bloch. In particular the rule for comparing {@code doubles},
   * {@code floats}, and arrays can be tricky. Also, making sure that
   * {@code equals()} and {@code hashCode()} are consistent can be
   * difficult.</p>
   *
   * <p>Two Objects that compare as equals must generate the same hash code,
   * but two Objects with the same hash code do not have to be equal.</p>
   *
   * <p>All relevant fields should be included in the calculation of equals.
   * Derived fields may be ignored. In particular, any field used in
   * generating a hash code must be used in the equals method, and vice
   * versa.</p>
   *
   * <p>Typical use for the code is as follows:</p>
   * <pre>
   * public boolean equals(Object obj) {
   *   if (obj == null) { return false; }
   *   if (obj == this) { return true; }
   *   if (obj.getClass() != getClass()) {
   *     return false;
   *   }
   *   MyClass rhs = (MyClass) obj;
   *   return new EqualsBuilder()
   *                 .appendSuper(super.equals(obj))
   *                 .append(field1, rhs.field1)
   *                 .append(field2, rhs.field2)
   *                 .append(field3, rhs.field3)
   *                 .isEquals();
   *  }
   * </pre>
   *
   * <p>Alternatively, there is a method that uses reflection to determine
   * the fields to test. Because these fields are usually private, the method,
   * {@code reflectionEquals}, uses {@code AccessibleObject.setAccessible} to
   * change the visibility of the fields. This will fail under a security
   * manager, unless the appropriate permissions are set up correctly. It is
   * also slower than testing explicitly.  Non-primitive fields are compared using
   * {@code equals()}.</p>
   *
   * <p>A typical invocation for this method would look like:</p>
   * <pre>
   * public boolean equals(Object obj) {
   *   return EqualsBuilder.reflectionEquals(this, obj);
   * }
   * </pre>
   *
   * <p>The {@link EqualsExclude} annotation can be used to exclude fields from being
   * used by the {@code reflectionEquals} methods.</p>
   *
   * @since 1.0
   */
  public class EqualsBuilder implements Builder<Boolean> {
  
      /**
       * A registry of objects used by reflection methods to detect cyclical object references and avoid infinite loops.
       *
       * @since 3.0
       */
      private static final ThreadLocal<Set<Pair<IDKey, IDKey>>> REGISTRY = ThreadLocal.withInitial(HashSet::new);
  
      /*
       * NOTE: we cannot store the actual objects in a HashSet, as that would use the very hashCode()
      * we are in the process of calculating.
      *
      * So we generate a one-to-one mapping from the original object to a new object.
      *
      * Now HashSet uses equals() to determine if two elements with the same hash code really
      * are equal, so we also need to ensure that the replacement objects are only equal
      * if the original objects are identical.
      *
      * The original implementation (2.4 and before) used the System.identityHashCode()
      * method - however this is not guaranteed to generate unique ids (e.g. LANG-459)
      *
      * We now use the IDKey helper class (adapted from org.apache.axis.utils.IDKey)
      * to disambiguate the duplicate ids.
      */
 
     /**
      * Converters value pair into a register pair.
      *
      * @param lhs {@code this} object
      * @param rhs the other object
      * @return the pair
      */
     static Pair<IDKey, IDKey> getRegisterPair(final Object lhs, final Object rhs) {
         return Pair.of(new IDKey(lhs), new IDKey(rhs));
     }
 
     /**
      * Gets the registry of object pairs being traversed by the reflection
      * methods in the current thread.
      *
      * @return Set the registry of objects being traversed
      * @since 3.0
      */
     static Set<Pair<IDKey, IDKey>> getRegistry() {
         return REGISTRY.get();
     }
 
     /**
      * Tests whether the registry contains the given object pair.
      * <p>
      * Used by the reflection methods to avoid infinite loops.
      * Objects might be swapped therefore a check is needed if the object pair
      * is registered in given or swapped order.
      * </p>
      *
      * @param lhs {@code this} object to lookup in registry
      * @param rhs the other object to lookup on registry
      * @return boolean {@code true} if the registry contains the given object.
      * @since 3.0
      */
     static boolean isRegistered(final Object lhs, final Object rhs) {
         final Set<Pair<IDKey, IDKey>> registry = getRegistry();
         final Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
         final Pair<IDKey, IDKey> swappedPair = Pair.of(pair.getRight(), pair.getLeft());
         return registry != null && (registry.contains(pair) || registry.contains(swappedPair));
     }
 
     /**
      * This method uses reflection to determine if the two {@link Object}s
      * are equal.
      *
      * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
      * fields. This means that it will throw a security exception if run under
      * a security manager, if the permissions are not set up correctly. It is also
      * not as efficient as testing explicitly. Non-primitive fields are compared using
      * {@code equals()}.</p>
      *
      * <p>If the TestTransients parameter is set to {@code true}, transient
      * members will be tested, otherwise they are ignored, as they are likely
      * derived fields, and not part of the value of the {@link Object}.</p>
      *
      * <p>Static fields will not be tested. Superclass fields will be included.</p>
      *
      * @param lhs  {@code this} object
      * @param rhs  the other object
      * @param testTransients  whether to include transient fields
      * @return {@code true} if the two Objects have tested equals.
      * @see EqualsExclude
      */
     public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients) {
         return reflectionEquals(lhs, rhs, testTransients, null);
     }
 
     /**
      * This method uses reflection to determine if the two {@link Object}s
      * are equal.
      *
      * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
      * fields. This means that it will throw a security exception if run under
      * a security manager, if the permissions are not set up correctly. It is also
      * not as efficient as testing explicitly. Non-primitive fields are compared using
      * {@code equals()}.</p>
      *
      * <p>If the testTransients parameter is set to {@code true}, transient
      * members will be tested, otherwise they are ignored, as they are likely
      * derived fields, and not part of the value of the {@link Object}.</p>
      *
      * <p>Static fields will not be included. Superclass fields will be appended
      * up to and including the specified superclass. A null superclass is treated
      * as java.lang.Object.</p>
      *
      * <p>If the testRecursive parameter is set to {@code true}, non primitive
      * (and non primitive wrapper) field types will be compared by
      * {@link EqualsBuilder} recursively instead of invoking their
      * {@code equals()} method. Leading to a deep reflection equals test.
      *
      * @param lhs  {@code this} object
      * @param rhs  the other object
      * @param testTransients  whether to include transient fields
      * @param reflectUpToClass  the superclass to reflect up to (inclusive),
      *  may be {@code null}
      * @param testRecursive  whether to call reflection equals on non-primitive
      *  fields recursively.
      * @param excludeFields  array of field names to exclude from testing
      * @return {@code true} if the two Objects have tested equals.
      * @see EqualsExclude
      * @since 3.6
      */
     public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients, final Class<?> reflectUpToClass,
             final boolean testRecursive, final String... excludeFields) {
         if (lhs == rhs) {
             return true;
         }
         if (lhs == null || rhs == null) {
             return false;
         }
         // @formatter:off
         return new EqualsBuilder()
             .setExcludeFields(excludeFields)
             .setReflectUpToClass(reflectUpToClass)
             .setTestTransients(testTransients)
             .setTestRecursive(testRecursive)
             .reflectionAppend(lhs, rhs)
             .isEquals();
         // @formatter:on
     }
 
     /**
      * This method uses reflection to determine if the two {@link Object}s
      * are equal.
      *
      * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
      * fields. This means that it will throw a security exception if run under
      * a security manager, if the permissions are not set up correctly. It is also
      * not as efficient as testing explicitly. Non-primitive fields are compared using
      * {@code equals()}.</p>
      *
      * <p>If the testTransients parameter is set to {@code true}, transient
      * members will be tested, otherwise they are ignored, as they are likely
      * derived fields, and not part of the value of the {@link Object}.</p>
      *
      * <p>Static fields will not be included. Superclass fields will be appended
      * up to and including the specified superclass. A null superclass is treated
      * as java.lang.Object.</p>
      *
      * @param lhs  {@code this} object
      * @param rhs  the other object
      * @param testTransients  whether to include transient fields
      * @param reflectUpToClass  the superclass to reflect up to (inclusive),
      *  may be {@code null}
      * @param excludeFields  array of field names to exclude from testing
      * @return {@code true} if the two Objects have tested equals.
      * @see EqualsExclude
      * @since 2.0
      */
     public static boolean reflectionEquals(final Object lhs, final Object rhs, final boolean testTransients, final Class<?> reflectUpToClass,
             final String... excludeFields) {
         return reflectionEquals(lhs, rhs, testTransients, reflectUpToClass, false, excludeFields);
     }
 
     /**
      * This method uses reflection to determine if the two {@link Object}s
      * are equal.
      *
      * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
      * fields. This means that it will throw a security exception if run under
      * a security manager, if the permissions are not set up correctly. It is also
      * not as efficient as testing explicitly. Non-primitive fields are compared using
      * {@code equals()}.</p>
      *
      * <p>Transient members will be not be tested, as they are likely derived
      * fields, and not part of the value of the Object.</p>
      *
      * <p>Static fields will not be tested. Superclass fields will be included.</p>
      *
      * @param lhs  {@code this} object
      * @param rhs  the other object
      * @param excludeFields  Collection of String field names to exclude from testing
      * @return {@code true} if the two Objects have tested equals.
      * @see EqualsExclude
      */
     public static boolean reflectionEquals(final Object lhs, final Object rhs, final Collection<String> excludeFields) {
         return reflectionEquals(lhs, rhs, ReflectionToStringBuilder.toNoNullStringArray(excludeFields));
     }
 
     /**
      * This method uses reflection to determine if the two {@link Object}s
      * are equal.
      *
      * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
      * fields. This means that it will throw a security exception if run under
      * a security manager, if the permissions are not set up correctly. It is also
      * not as efficient as testing explicitly. Non-primitive fields are compared using
      * {@code equals()}.</p>
      *
      * <p>Transient members will be not be tested, as they are likely derived
      * fields, and not part of the value of the Object.</p>
      *
      * <p>Static fields will not be tested. Superclass fields will be included.</p>
      *
      * @param lhs  {@code this} object
      * @param rhs  the other object
      * @param excludeFields  array of field names to exclude from testing
      * @return {@code true} if the two Objects have tested equals.
      * @see EqualsExclude
      */
     public static boolean reflectionEquals(final Object lhs, final Object rhs, final String... excludeFields) {
         return reflectionEquals(lhs, rhs, false, null, excludeFields);
     }
 
     /**
      * Registers the given object pair.
      * Used by the reflection methods to avoid infinite loops.
      *
      * @param lhs {@code this} object to register
      * @param rhs the other object to register
      */
     private static void register(final Object lhs, final Object rhs) {
         getRegistry().add(getRegisterPair(lhs, rhs));
     }
 
     /**
      * Unregisters the given object pair.
      *
      * <p>
      * Used by the reflection methods to avoid infinite loops.
      * </p>
      *
      * @param lhs {@code this} object to unregister
      * @param rhs the other object to unregister
      * @since 3.0
      */
     private static void unregister(final Object lhs, final Object rhs) {
         final Set<Pair<IDKey, IDKey>> registry = getRegistry();
         registry.remove(getRegisterPair(lhs, rhs));
         if (registry.isEmpty()) {
             REGISTRY.remove();
         }
     }
 
     /**
      * If the fields tested are equals.
      * The default value is {@code true}.
      */
     private boolean isEquals = true;
 
     private boolean testTransients;
 
     private boolean testRecursive;
 
     private List<Class<?>> bypassReflectionClasses;
 
     private Class<?> reflectUpToClass;
 
     private String[] excludeFields;
 
     /**
      * Constructor for EqualsBuilder.
      *
      * <p>Starts off assuming that equals is {@code true}.</p>
      * @see Object#equals(Object)
      */
     public EqualsBuilder() {
         // set up default classes to bypass reflection for
         bypassReflectionClasses = new ArrayList<>(1);
         bypassReflectionClasses.add(String.class); //hashCode field being lazy but not transient
     }
 
     /**
      * Test if two {@code booleans}s are equal.
      *
      * @param lhs  the left-hand side {@code boolean}
      * @param rhs  the right-hand side {@code boolean}
      * @return {@code this} instance.
       */
     public EqualsBuilder append(final boolean lhs, final boolean rhs) {
         if (!isEquals) {
             return this;
         }
         isEquals = lhs == rhs;
         return this;
     }
 
     /**
      * Deep comparison of array of {@code boolean}. Length and all
      * values are compared.
      *
      * <p>The method {@link #append(boolean, boolean)} is used.</p>
      *
      * @param lhs  the left-hand side {@code boolean[]}
      * @param rhs  the right-hand side {@code boolean[]}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final boolean[] lhs, final boolean[] rhs) {
         if (!isEquals) {
             return this;
         }
         if (lhs == rhs) {
             return this;
         }
         if (lhs == null || rhs == null) {
             setEquals(false);
             return this;
         }
         if (lhs.length != rhs.length) {
             setEquals(false);
             return this;
         }
         for (int i = 0; i < lhs.length && isEquals; ++i) {
             append(lhs[i], rhs[i]);
         }
         return this;
     }
 
     /**
      * Test if two {@code byte}s are equal.
      *
      * @param lhs  the left-hand side {@code byte}
      * @param rhs  the right-hand side {@code byte}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final byte lhs, final byte rhs) {
         if (isEquals) {
             isEquals = lhs == rhs;
         }
         return this;
     }
 
     /**
      * Deep comparison of array of {@code byte}. Length and all
      * values are compared.
      *
      * <p>The method {@link #append(byte, byte)} is used.</p>
      *
      * @param lhs  the left-hand side {@code byte[]}
      * @param rhs  the right-hand side {@code byte[]}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final byte[] lhs, final byte[] rhs) {
         if (!isEquals) {
             return this;
         }
         if (lhs == rhs) {
             return this;
         }
         if (lhs == null || rhs == null) {
             setEquals(false);
             return this;
         }
         if (lhs.length != rhs.length) {
             setEquals(false);
             return this;
         }
         for (int i = 0; i < lhs.length && isEquals; ++i) {
             append(lhs[i], rhs[i]);
         }
         return this;
     }
 
     /**
      * Test if two {@code char}s are equal.
      *
      * @param lhs  the left-hand side {@code char}
      * @param rhs  the right-hand side {@code char}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final char lhs, final char rhs) {
         if (isEquals) {
             isEquals = lhs == rhs;
         }
         return this;
     }
 
     /**
      * Deep comparison of array of {@code char}. Length and all
      * values are compared.
      *
      * <p>The method {@link #append(char, char)} is used.</p>
      *
      * @param lhs  the left-hand side {@code char[]}
      * @param rhs  the right-hand side {@code char[]}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final char[] lhs, final char[] rhs) {
         if (!isEquals) {
             return this;
         }
         if (lhs == rhs) {
             return this;
         }
         if (lhs == null || rhs == null) {
             setEquals(false);
             return this;
         }
         if (lhs.length != rhs.length) {
             setEquals(false);
             return this;
         }
         for (int i = 0; i < lhs.length && isEquals; ++i) {
             append(lhs[i], rhs[i]);
         }
         return this;
     }
 
     /**
      * Test if two {@code double}s are equal by testing that the
      * pattern of bits returned by {@code doubleToLong} are equal.
      *
      * <p>This handles NaNs, Infinities, and {@code -0.0}.</p>
      *
      * <p>It is compatible with the hash code generated by
      * {@link HashCodeBuilder}.</p>
      *
      * @param lhs  the left-hand side {@code double}
      * @param rhs  the right-hand side {@code double}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final double lhs, final double rhs) {
         if (isEquals) {
             return append(Double.doubleToLongBits(lhs), Double.doubleToLongBits(rhs));
         }
         return this;
     }
 
     /**
      * Deep comparison of array of {@code double}. Length and all
      * values are compared.
      *
      * <p>The method {@link #append(double, double)} is used.</p>
      *
      * @param lhs  the left-hand side {@code double[]}
      * @param rhs  the right-hand side {@code double[]}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final double[] lhs, final double[] rhs) {
         if (!isEquals) {
             return this;
         }
         if (lhs == rhs) {
             return this;
         }
         if (lhs == null || rhs == null) {
             setEquals(false);
             return this;
         }
         if (lhs.length != rhs.length) {
             setEquals(false);
             return this;
         }
         for (int i = 0; i < lhs.length && isEquals; ++i) {
             append(lhs[i], rhs[i]);
         }
         return this;
     }
 
     /**
      * Test if two {@code float}s are equal by testing that the
      * pattern of bits returned by doubleToLong are equal.
      *
      * <p>This handles NaNs, Infinities, and {@code -0.0}.</p>
      *
      * <p>It is compatible with the hash code generated by
      * {@link HashCodeBuilder}.</p>
      *
      * @param lhs  the left-hand side {@code float}
      * @param rhs  the right-hand side {@code float}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final float lhs, final float rhs) {
         if (isEquals) {
             return append(Float.floatToIntBits(lhs), Float.floatToIntBits(rhs));
         }
         return this;
     }
 
     /**
      * Deep comparison of array of {@code float}. Length and all
      * values are compared.
      *
      * <p>The method {@link #append(float, float)} is used.</p>
      *
      * @param lhs  the left-hand side {@code float[]}
      * @param rhs  the right-hand side {@code float[]}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final float[] lhs, final float[] rhs) {
         if (!isEquals) {
             return this;
         }
         if (lhs == rhs) {
             return this;
         }
         if (lhs == null || rhs == null) {
             setEquals(false);
             return this;
         }
         if (lhs.length != rhs.length) {
             setEquals(false);
             return this;
         }
         for (int i = 0; i < lhs.length && isEquals; ++i) {
             append(lhs[i], rhs[i]);
         }
         return this;
     }
 
     /**
      * Test if two {@code int}s are equal.
      *
      * @param lhs  the left-hand side {@code int}
      * @param rhs  the right-hand side {@code int}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final int lhs, final int rhs) {
         if (isEquals) {
             isEquals = lhs == rhs;
         }
         return this;
     }
 
     /**
      * Deep comparison of array of {@code int}. Length and all
      * values are compared.
      *
      * <p>The method {@link #append(int, int)} is used.</p>
      *
      * @param lhs  the left-hand side {@code int[]}
      * @param rhs  the right-hand side {@code int[]}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final int[] lhs, final int[] rhs) {
         if (!isEquals) {
             return this;
         }
         if (lhs == rhs) {
             return this;
         }
         if (lhs == null || rhs == null) {
             setEquals(false);
             return this;
         }
         if (lhs.length != rhs.length) {
             setEquals(false);
             return this;
         }
         for (int i = 0; i < lhs.length && isEquals; ++i) {
             append(lhs[i], rhs[i]);
         }
         return this;
     }
 
     /**
      * Test if two {@code long}s are equal.
      *
      * @param lhs
      *                  the left-hand side {@code long}
      * @param rhs
      *                  the right-hand side {@code long}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final long lhs, final long rhs) {
         if (isEquals) {
             isEquals = lhs == rhs;
         }
         return this;
     }
 
     /**
      * Deep comparison of array of {@code long}. Length and all
      * values are compared.
      *
      * <p>The method {@link #append(long, long)} is used.</p>
      *
      * @param lhs  the left-hand side {@code long[]}
      * @param rhs  the right-hand side {@code long[]}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final long[] lhs, final long[] rhs) {
         if (!isEquals) {
             return this;
         }
         if (lhs == rhs) {
             return this;
         }
         if (lhs == null || rhs == null) {
             setEquals(false);
             return this;
         }
         if (lhs.length != rhs.length) {
             setEquals(false);
             return this;
         }
         for (int i = 0; i < lhs.length && isEquals; ++i) {
             append(lhs[i], rhs[i]);
         }
         return this;
     }
 
     /**
      * Test if two {@link Object}s are equal using either
      * #{@link #reflectionAppend(Object, Object)}, if object are non
      * primitives (or wrapper of primitives) or if field {@code testRecursive}
      * is set to {@code false}. Otherwise, using their
      * {@code equals} method.
      *
      * @param lhs  the left-hand side object
      * @param rhs  the right-hand side object
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final Object lhs, final Object rhs) {
         if (!isEquals) {
             return this;
         }
         if (lhs == rhs) {
             return this;
         }
         if (lhs == null || rhs == null) {
             setEquals(false);
             return this;
         }
         final Class<?> lhsClass = lhs.getClass();
         if (lhsClass.isArray()) {
             // factor out array case in order to keep method small enough
             // to be inlined
             appendArray(lhs, rhs);
         } else // The simple case, not an array, just test the element
         if (testRecursive && !ClassUtils.isPrimitiveOrWrapper(lhsClass)) {
             reflectionAppend(lhs, rhs);
         } else {
             isEquals = lhs.equals(rhs);
         }
         return this;
     }
 
     /**
      * Performs a deep comparison of two {@link Object} arrays.
      *
      * <p>This also will be called for the top level of
      * multi-dimensional, ragged, and multi-typed arrays.</p>
      *
      * <p>Note that this method does not compare the type of the arrays; it only
      * compares the contents.</p>
      *
      * @param lhs  the left-hand side {@code Object[]}
      * @param rhs  the right-hand side {@code Object[]}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final Object[] lhs, final Object[] rhs) {
         if (!isEquals) {
             return this;
         }
         if (lhs == rhs) {
             return this;
         }
         if (lhs == null || rhs == null) {
             setEquals(false);
             return this;
         }
         if (lhs.length != rhs.length) {
             setEquals(false);
             return this;
         }
         for (int i = 0; i < lhs.length && isEquals; ++i) {
             append(lhs[i], rhs[i]);
         }
         return this;
     }
 
     /**
      * Test if two {@code short}s are equal.
      *
      * @param lhs  the left-hand side {@code short}
      * @param rhs  the right-hand side {@code short}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final short lhs, final short rhs) {
         if (isEquals) {
             isEquals = lhs == rhs;
         }
         return this;
     }
 
     /**
      * Deep comparison of array of {@code short}. Length and all
      * values are compared.
      *
      * <p>The method {@link #append(short, short)} is used.</p>
      *
      * @param lhs  the left-hand side {@code short[]}
      * @param rhs  the right-hand side {@code short[]}
      * @return {@code this} instance.
      */
     public EqualsBuilder append(final short[] lhs, final short[] rhs) {
         if (!isEquals) {
             return this;
         }
         if (lhs == rhs) {
             return this;
         }
         if (lhs == null || rhs == null) {
             setEquals(false);
             return this;
         }
         if (lhs.length != rhs.length) {
             setEquals(false);
             return this;
         }
         for (int i = 0; i < lhs.length && isEquals; ++i) {
             append(lhs[i], rhs[i]);
         }
         return this;
     }
 
     /**
      * Test if an {@link Object} is equal to an array.
      *
      * @param lhs  the left-hand side object, an array
      * @param rhs  the right-hand side object
      */
     private void appendArray(final Object lhs, final Object rhs) {
         // First we compare different dimensions, for example: a boolean[][] to a boolean[]
         // then we 'Switch' on type of array, to dispatch to the correct handler
         // This handles multidimensional arrays of the same depth
         if (lhs.getClass() != rhs.getClass()) {
             setEquals(false);
         } else if (lhs instanceof long[]) {
             append((long[]) lhs, (long[]) rhs);
         } else if (lhs instanceof int[]) {
             append((int[]) lhs, (int[]) rhs);
         } else if (lhs instanceof short[]) {
             append((short[]) lhs, (short[]) rhs);
         } else if (lhs instanceof char[]) {
             append((char[]) lhs, (char[]) rhs);
         } else if (lhs instanceof byte[]) {
             append((byte[]) lhs, (byte[]) rhs);
         } else if (lhs instanceof double[]) {
             append((double[]) lhs, (double[]) rhs);
         } else if (lhs instanceof float[]) {
             append((float[]) lhs, (float[]) rhs);
         } else if (lhs instanceof boolean[]) {
             append((boolean[]) lhs, (boolean[]) rhs);
         } else {
             // Not an array of primitives
             append((Object[]) lhs, (Object[]) rhs);
         }
     }
 
     /**
      * Adds the result of {@code super.equals()} to this builder.
      *
      * @param superEquals  the result of calling {@code super.equals()}
      * @return {@code this} instance.
      * @since 2.0
      */
     public EqualsBuilder appendSuper(final boolean superEquals) {
         if (!isEquals) {
             return this;
         }
         isEquals = superEquals;
         return this;
     }
 
     /**
      * Returns {@code true} if the fields that have been checked
      * are all equal.
      *
      * @return {@code true} if all of the fields that have been checked
      *         are equal, {@code false} otherwise.
      *
      * @since 3.0
      */
     @Override
     public Boolean build() {
         return Boolean.valueOf(isEquals());
     }
 
     /**
      * Returns {@code true} if the fields that have been checked
      * are all equal.
      *
      * @return boolean
      */
     public boolean isEquals() {
         return isEquals;
     }
 
     /**
      * Tests if two {@code objects} by using reflection.
      *
      * <p>It uses {@code AccessibleObject.setAccessible} to gain access to private
      * fields. This means that it will throw a security exception if run under
      * a security manager, if the permissions are not set up correctly. It is also
      * not as efficient as testing explicitly. Non-primitive fields are compared using
      * {@code equals()}.</p>
      *
      * <p>If the testTransients field is set to {@code true}, transient
      * members will be tested, otherwise they are ignored, as they are likely
      * derived fields, and not part of the value of the {@link Object}.</p>
      *
      * <p>Static fields will not be included. Superclass fields will be appended
      * up to and including the specified superclass in field {@code reflectUpToClass}.
      * A null superclass is treated as java.lang.Object.</p>
      *
      * <p>Field names listed in field {@code excludeFields} will be ignored.</p>
      *
      * <p>If either class of the compared objects is contained in
      * {@code bypassReflectionClasses}, both objects are compared by calling
      * the equals method of the left-hand side object with the right-hand side object as an argument.</p>
      *
      * @param lhs  the left-hand side object
      * @param rhs  the right-hand side object
      * @return {@code this} instance.
      */
     public EqualsBuilder reflectionAppend(final Object lhs, final Object rhs) {
         if (!isEquals) {
             return this;
         }
         if (lhs == rhs) {
             return this;
         }
         if (lhs == null || rhs == null) {
             isEquals = false;
             return this;
         }
 
         // Find the leaf class since there may be transients in the leaf
         // class or in classes between the leaf and root.
         // If we are not testing transients or a subclass has no ivars,
         // then a subclass can test equals to a superclass.
         final Class<?> lhsClass = lhs.getClass();
         final Class<?> rhsClass = rhs.getClass();
         Class<?> testClass;
         if (lhsClass.isInstance(rhs)) {
             testClass = lhsClass;
             if (!rhsClass.isInstance(lhs)) {
                 // rhsClass is a subclass of lhsClass
                 testClass = rhsClass;
             }
         } else if (rhsClass.isInstance(lhs)) {
             testClass = rhsClass;
             if (!lhsClass.isInstance(rhs)) {
                 // lhsClass is a subclass of rhsClass
                 testClass = lhsClass;
             }
         } else {
             // The two classes are not related.
             isEquals = false;
             return this;
         }
 
         try {
             if (testClass.isArray()) {
                 append(lhs, rhs);
             } else //If either class is being excluded, call normal object equals method on lhsClass.
             if (bypassReflectionClasses != null
                     && (bypassReflectionClasses.contains(lhsClass) || bypassReflectionClasses.contains(rhsClass))) {
                 isEquals = lhs.equals(rhs);
             } else {
                 reflectionAppend(lhs, rhs, testClass);
                 while (testClass.getSuperclass() != null && testClass != reflectUpToClass) {
                     testClass = testClass.getSuperclass();
                     reflectionAppend(lhs, rhs, testClass);
                 }
             }
         } catch (final IllegalArgumentException e) {
             // In this case, we tried to test a subclass vs. a superclass and
             // the subclass has ivars or the ivars are transient and
             // we are testing transients.
             // If a subclass has ivars that we are trying to test them, we get an
             // exception and we know that the objects are not equal.
             isEquals = false;
         }
         return this;
     }
 
     /**
      * Appends the fields and values defined by the given object of the
      * given Class.
      *
      * @param lhs  the left-hand side object
      * @param rhs  the right-hand side object
      * @param clazz  the class to append details of
      */
     private void reflectionAppend(
         final Object lhs,
         final Object rhs,
         final Class<?> clazz) {
 
         if (isRegistered(lhs, rhs)) {
             return;
         }
 
         try {
             register(lhs, rhs);
             final Field[] fields = clazz.getDeclaredFields();
             AccessibleObject.setAccessible(fields, true);
             for (int i = 0; i < fields.length && isEquals; i++) {
                 final Field field = fields[i];
                 if (!ArrayUtils.contains(excludeFields, field.getName())
                     && !field.getName().contains("$")
                     && (testTransients || !Modifier.isTransient(field.getModifiers()))
                     && !Modifier.isStatic(field.getModifiers())
                     && !field.isAnnotationPresent(EqualsExclude.class)) {
                     append(Reflection.getUnchecked(field, lhs), Reflection.getUnchecked(field, rhs));
                 }
             }
         } finally {
             unregister(lhs, rhs);
         }
     }
 
     /**
      * Reset the EqualsBuilder so you can use the same object again.
      *
      * @since 2.5
      */
     public void reset() {
         isEquals = true;
     }
 
     /**
      * Sets {@link Class}es whose instances should be compared by calling their {@code equals}
      * although being in recursive mode. So the fields of these classes will not be compared recursively by reflection.
      *
      * <p>Here you should name classes having non-transient fields which are cache fields being set lazily.<br>
      * Prominent example being {@link String} class with its hash code cache field. Due to the importance
      * of the {@link String} class, it is included in the default bypasses classes. Usually, if you use
      * your own set of classes here, remember to include {@link String} class, too.</p>
      *
      * @param bypassReflectionClasses  classes to bypass reflection test
      * @return {@code this} instance.
      * @see #setTestRecursive(boolean)
      * @since 3.8
      */
     public EqualsBuilder setBypassReflectionClasses(final List<Class<?>> bypassReflectionClasses) {
         this.bypassReflectionClasses = bypassReflectionClasses;
         return this;
     }
 
     /**
      * Sets the {@code isEquals} value.
      *
      * @param isEquals The value to set.
      * @since 2.1
      */
     protected void setEquals(final boolean isEquals) {
         this.isEquals = isEquals;
     }
 
     /**
      * Sets field names to be excluded by reflection tests.
      *
      * @param excludeFields the fields to exclude
      * @return {@code this} instance.
      * @since 3.6
      */
     public EqualsBuilder setExcludeFields(final String... excludeFields) {
         this.excludeFields = excludeFields;
         return this;
     }
 
     /**
      * Sets the superclass to reflect up to at reflective tests.
      *
      * @param reflectUpToClass the super class to reflect up to
      * @return {@code this} instance.
      * @since 3.6
      */
     public EqualsBuilder setReflectUpToClass(final Class<?> reflectUpToClass) {
         this.reflectUpToClass = reflectUpToClass;
         return this;
     }
 
     /**
      * Sets whether to test fields recursively, instead of using their equals method, when reflectively comparing objects.
      * String objects, which cache a hash value, are automatically excluded from recursive testing.
      * You may specify other exceptions by calling {@link #setBypassReflectionClasses(List)}.
      *
      * @param testRecursive whether to do a recursive test
      * @return {@code this} instance.
      * @see #setBypassReflectionClasses(List)
      * @since 3.6
      */
     public EqualsBuilder setTestRecursive(final boolean testRecursive) {
         this.testRecursive = testRecursive;
         return this;
     }
 
     /**
      * Sets whether to include transient fields when reflectively comparing objects.
      *
      * @param testTransients whether to test transient fields
      * @return {@code this} instance.
      * @since 3.6
      */
     public EqualsBuilder setTestTransients(final boolean testTransients) {
         this.testTransients = testTransients;
         return this;
     }
 }