@Override
    public void start(CoprocessorEnvironment env) throws IOException {
      // At start, we get base CoprocessorEnvironment Type, not RegionCoprocessorEnvironment,
      checkShared(((RegionCoprocessorEnvironment) env).getConnection());
    }
Start up a mini cluster with my three CPs loaded.
hbase-server/src/test/java/org/apache/hadoop/hbase/coprocessor/TestCoprocessorSharedConnection.java