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

Cobertura is a free Java tool that calculates the percentage of code accessed by tests. It can be used to identify which parts of your Java program are lacking test coverage.

PMD Java

PMD Core

Mondrian OLAP Engine

GATE - general architecture for text engineering - is open source software capable of solving almost any text processing problem. This artifact enables you to embed the core GATE Embedded with its essential dependencies.

Avro

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.

PMD JSP