protected void destroyProcess(Process p) {
        if (p == null) {
            return;
        }

        try {
            p.exitValue();
        } catch (IllegalThreadStateException e) {
            p.destroy();
        }
    }
helper method equivalent to File#listFiles()
grabs children only, does not walk recursively

@param p
@return
tika-batch/src/test/java/org/apache/tika/batch/fs/FSBatchTestBase.java