code: @Override
      public RawCollationKey getRawCollationKey(String source, RawCollationKey key) {
          if (source == null) {
              return null;
          }
          CollationBuffer buffer = null;
          try {
              buffer = getCollationBuffer();
              return getRawCollationKey(source, key, buffer);
          } finally {
              releaseCollationBuffer(buffer);
          }
      }
docs: Gets the simpler form of a CollationKey for the String source following the rules of this Collator and stores the
  result into the user provided argument key. If key has a internal byte array of length that's too small for the
  result, the internal byte array will be grown to the exact required size.
  
  @param source the text String to be transformed into a RawCollationKey
  @param key output RawCollationKey to store results
  @return If key is null, a new instance of RawCollationKey will be created and returned, otherwise the user
  provided key will be returned.
  @see #getCollationKey
  @see #compare(String, String)
  @see RawCollationKey
  @hide unsupported on Android