code: public static <T, R> Optional<R> getOptionalIfExist(Optional<T> optional,
              Function<T, R> returnBuilderFunction) {
          return optional.map(returnBuilderFunction);
      }
docs: Gets optional if exist.
  
  @param <T>                   the type parameter
  @param <R>                   the type parameter
  @param optional              the optional
  @param returnBuilderFunction the return builder function
  @return the optional if exist