code: public void releaseConnection() {
          LOG.trace("enter HttpConnection.releaseConnection()");
          if (locked) {
              LOG.debug("Connection is locked.  Call to releaseConnection() ignored.");
          } else if (httpConnectionManager != null) {
              LOG.debug("Releasing connection back to connection manager.");
              httpConnectionManager.releaseConnection(this);
          } else {
              LOG.warn("HttpConnectionManager is null.  Connection cannot be released.");
          }
      }
docs: Releases the connection. If the connection is locked or does not have a connection
  manager associated with it, this method has no effect. Note that it is completely safe
  to call this method multiple times.