@Override
    public CompactionContext answer(InvocationOnMock invocation) throws Throwable {
      cancelCompaction(invocation.getArgument(0));
      return null;
    }
This class is a helper that allows to create a partially-implemented, stateful mocks of Store. It
contains a bunch of blank methods, and answers redirecting to these.
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/StatefulStoreMockMaker.java