code: public static CompleteFileContext mergeFrom(CompleteFilePOptions.Builder optionsBuilder) {
      CompleteFilePOptions masterOptions = FileSystemMasterOptions.completeFileDefaults();
      CompleteFilePOptions.Builder mergedOptionsBuilder =
          masterOptions.toBuilder().mergeFrom(optionsBuilder.build());
      return create(mergedOptionsBuilder);
    }
docs: Merges and embeds the given {@link CompleteFilePOptions} with the corresponding master options.
  
  @param optionsBuilder Builder for proto {@link CompleteFilePOptions} to merge with defaults
  @return the instance of {@link CompleteFileContext} with default values for master