Fixes for new Lombok & Eclipse compatibility

• Added org.eclipse.jdt.annotation Nullable & NonNull annotations because they may sometimes be generated by Lombok (annos marked as deprecated)
• Updated javadoc generation in pom.xml for new Eclipse compatibility (uses newer plugin version)

Changed annotations to be retained at runtime

Changed annotations to be retained at runtime as those are useful for runtime code analysis (such as JavaBeans validation).

NonNullByDefault repackaged for better compatibility between Eclipse & IDEA IDEs

BREAKING CHANGE: javax.annotation.NonNullByDefault is now org.eclipse.jdt.annotation.NonNullByDefault to provide the best support across Eclipse & IDEA IDEs (due to their limitations).

It is still non-standard Eclipse annotation because it also declares ARRAY_CONTENTS as non-null by default.

IntelliJ Idea support

Added support for IntelliJ Idea to @NonNullByDefault