code: public synchronized Chain getRunningChain(String chainName) {
          Chain chain = null;
          if (null != chainName) {
              chain = this.chainRunningMap.get(chainName);
          }
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
              Tr.debug(tc, "getRunningChain: " + chainName + " found=" + (null != chain));
          }
          return chain;
      }
docs: Fetch the input chain from the runtime.
  
  @param chainName
  @return chain requested, or null if not found.