public static Set<String> getLoadedCoprocessors() {
    synchronized (coprocessorNames) {
      return new HashSet(coprocessorNames);
    }
  }
Not to be confused with the per-object _coprocessors_ (above), coprocessorNames is static and
stores the set of all coprocessors ever loaded by any thread in this JVM. It is strictly
additive: coprocessors are added to coprocessorNames, by checkAndLoadInstance() but are never
removed, since the intention is to preserve a history of all loaded coprocessors for diagnosis
in case of server crash (HBASE-4014).
hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/CoprocessorHost.java