Contributions of all sorts are welcome, but to be useful has to follow certain conventions. Some of those ( :-) ) are described here.
Most importantly, this project is intended to be portable, meaning to run equally good on all supported platforms (to the extent possible). Therefore, features running only on one particular platform are not a priority -- which does not exclude the best possible integration in a particular platform. But they are not prohibited either.
The code uses "normal Java formatting": Indentation 4 spaces, no tabs. Braces in simple if-statements (etc) discouraged. No linefeed before opening brace. The "principle of locality" is to be observed: Distance between declaration and usage should be minimal; C style declaration of local variables in the beginning of a block discouraged.
Apache Maven is used for builds.
Normal builds must not require Internet access.
All parameters (URLs, version numbers etc.) should be contained therein within /project/properties.
(Other programs can then extract that information, see common/xslt/extract_project_version.xsl for an example.)