Checkstyle suppression is too broad and skips all .java files

[wilkinsona]

This:

<suppress files=".+\.[jar|git|ico|p12|svg|png]" checks=".*" />

Should be this:

<suppress files=".+\.(jar|git|ico|p12|svg|png)" checks=".*" />

[wilkinsona]

Fixing this has revealed some violations that now need to be addressed.

[philwebb]

@wilkinsona I think these have now been sorted.

[wilkinsona]

Agreed.