@SuppressWarnings("unchecked") is used too generally

@SuppressWarnings("unchecked") is used in several places on entire methods.
Mostly there is no documentation as to why it is safe to ignore the warnings.

Seems to me the annotation should be used as close as possible to the site of the warning, and the reason should be documented, so it can be revisited if there is a code change later.

In fact, at least one of the warnings is NOT safe to ignore:

String[] s = ArrayUtils.add((String[])null, null);

generates a ClassCastException, which should not happen if the warning is OK to ignore.