update errorprone.
<!-- Google error-prone
Compiler adaptor with some useful checks for common errors. -->
- <dependency org="com.google.errorprone" name="error_prone_ant" rev="2.2.0" transitive="false" conf="build->default" />
- <dependency org="com.google.errorprone" name="error_prone_annotations" rev="2.2.0" conf="build->default; contrib->sources" />
+ <dependency org="com.google.errorprone" name="error_prone_ant" rev="2.3.1" transitive="false" conf="build->default" />
+ <dependency org="com.google.errorprone" name="error_prone_annotations" rev="2.3.1" conf="build->default; contrib->sources" />
<!-- Eclipse JDT Compiler
For additional compiler warnings. -->
