Do not use Java 1.6 API

Since the plugin specifies Java 1.5 compatability, I configured a "real" JDK 1.5 as runtime for the project. Some compile errors came up that acutally use Java 6 API.

IMHO, if we claim JDK 1.5 compatability, we should not use newer API. Or you just ditch this pull request and update the plugin to Java 6 compatability ...