code: protected final void _mergeProperties(Properties implementationSpecificProperties) {
          for (Entry<Object, Object> entry : implementationSpecificProperties.entrySet()) {
              _configuration.putIfAbsent(entry.getKey(), entry.getValue());
          }
      }
docs: Merges the implementation specific service configuration properties with the system level configuration properties. This method examines the
  implementation specific service configuration property keys as obtained by the <tt>getServiceProperties()</tt> method and determines if the
  system configuration contains the property. If the system configuration does not contain the property, the method inserts the default value
  specified in the result of <tt>getServiceProperties()</tt> method into the system configuration.
  
  @param implementationSpecificProperties The implementation specific service configuration property defaults to merge if they are absent from
  the system configuration.