Update to 2.3.1

https://repo1.maven.org/maven2/com/google/errorprone/error_prone_ant/2.3.1/
1 file changed
tree: a71dc7a8d4b7b4a5ba8e0c6de22dcd6f3232433a
  1. error_prone_ant-2.3.1.jar
  2. LICENSE
  3. README.chromium