JavaCC is a parser/scanner generator for java.

Avro is a row-oriented remote procedure call and data serialization framework that produces a compact binary format.

ZooKeeper server

The core parser functionality. This may be all you need.

JSqlParser parses an SQL statement and translate it into a hierarchy of Java classes. The generated hierarchy can be navigated using the Visitor Pattern.

Jackrabbit content repository implementation

PMD Java

PMD Core

Jackrabbit SPI Commons

PMD is an extensible multilanguage static code analyzer. It finds common programming flaws like unused variables, empty catch blocks, unnecessary object creation, and so forth.

Jackson JQ