code: public static void removeAll(final Iterable<String> keys) {
          if (contextMap instanceof CleanableThreadContextMap) {
              ((CleanableThreadContextMap) contextMap).removeAll(keys);
          } else if (contextMap instanceof DefaultThreadContextMap) {
              ((DefaultThreadContextMap) contextMap).removeAll(keys);
          } else {
              for (final String key : keys) {
                  contextMap.remove(key);
              }
          }
      }
docs: Removes the context values identified by the <code>keys</code> parameter.
  
  @param keys The keys to remove.
  
  @since 2.8