code: @Override
      public Object getProperty(IClientConfigKey key, Object defaultVal){
          Object val = getProperty(key);
          if (val == null){
              return defaultVal;
          }
          return val;
      }
docs: /* (non-Javadoc)
  @see com.netflix.niws.client.CliengConfig#getProperty(com.netflix.niws.client.ClientConfigKey, java.lang.Object)