@Test
  public void testCoreRegionCoprocessor() throws IOException {
    RegionCoprocessorHost rch = region.getCoprocessorHost();
    RegionCoprocessorEnvironment env =
      rch.load(null, NotCoreRegionCoprocessor.class.getName(), 0, HTU.getConfiguration());
    assertFalse(env instanceof HasRegionServerServices);
    env = rch.load(null, CoreRegionCoprocessor.class.getName(), 1, HTU.getConfiguration());
    assertTrue(env instanceof HasRegionServerServices);
    assertEquals(this.rss, ((HasRegionServerServices) env).getRegionServerServices());
  }
Assert that when a Coprocessor is annotated with CoreCoprocessor, then it is possible to access
a RegionServerServices instance. Assert the opposite too. Do it to RegionCoprocessors.
hbase-server/src/test/java/org/apache/hadoop/hbase/coprocessor/TestCoreRegionCoprocessor.java