code: public static <T> boolean optMergeDelimitedFrom(InputStream in,
              T message, Schema<T> schema,
              LinkedBuffer buffer) throws IOException
      {
          return optMergeDelimitedFrom(in, message, schema, true, buffer);
      }
docs: Optimal/Optional mergeDelimitedFrom - If the message does not fit the buffer, no merge is done and this method
  will return false.
  <p>
  This is strictly for reading a single message from the stream because the buffer is aggressively filled when
  reading the delimited size (which could result into reading more bytes than it has to).
  <p>
  The remaining bytes will be drained (consumed and discared) when the message is too large.