http://github.com/FasterXML/jackson-dataformats-binary: Support for reading and writing protobuf-encoded data via Jackson abstractions. (FasterXML)
  • Tatu Saloranta 
Contains functionality for generating Protobuf schema instances
from POJO definitions, instead of reading external protoc definitions.
This may be useful as-is, or for actually generating protoc definitions
with code-first approach.

/**
 * Contains functionality for generating Protobuf schema instances
 * from POJO definitions, instead of reading external protoc definitions.
 * This may be useful as-is, or for actually generating protoc definitions
 * with code-first approach.
 */
package com.fasterxml.jackson.dataformat.protobuf.schemagen;