package com.atlassian.scheduler.util;
   
   import com.atlassian.annotations.Internal;
   import com.google.common.collect.ImmutableMap;
   
   import javax.annotation.Nonnull;
   import javax.annotation.Nullable;
   import java.io.Serializable;
   import java.util.Collections;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.Map;
  
  /**
   * Static utility methods for things like {@code null}-testing and defensive copies.
   *
   * @since v1.0
   */
  @Internal
  public final class Safe {
      /**
       * Make a defensive copy of a mutable {@link Date}.
       */
      @Nullable
      public static Date copy(@Nullable Date date) {
          return (date != null) ? (Date) date.clone() : null;
      }
  
      /**
       * Make a defensive copy of a byte array.
       */
      @Nullable
      public static byte[] copy(@Nullable final byte[] bytes) {
          return (bytes != null) ? bytes.clone() : null;
      }
  
      /**
       * Make a defensive copy of a possibly mutable map.  An empty map is substituted
       * for {@code null}.
       */
      @Nonnull
      public static Map<String, Serializable> copy(@Nullable final Map<String, Serializable> map) {
          final Map<String, Serializable> copy;
          if (map == null) {
              copy = ImmutableMap.of();
          } else if (map instanceof ImmutableMap) {
              copy = map;
          } else {
              copy = Collections.unmodifiableMap(new HashMap<String, Serializable>(map));
          }
          return copy;
      }
  
      private Safe() {
          throw new Error("I am static-only.");
      }
  }