code: private void importFromProperties(final URL _url)
      {
          try {
              final InputStream propInFile = _url.openStream();
              final Properties props = new Properties();
              props.load(propInFile);
              final Iterator<Entry<Object, Object>> iter = props.entrySet().iterator();
  
              while (iter.hasNext()) {
                  final Entry<Object, Object> element = iter.next();
                  final Instance existing = getExistingKey(element.getKey().toString());
                  if (existing == null) {
                      insertNewProp(element.getKey().toString(), element.getValue().toString());
                  } else {
                      updateDefault(existing, element.getValue().toString());
                  }
              }
  
          } catch (final IOException e) {
              DBPropertiesUpdate.LOG.error("ImportFromProperties() - I/O failed.", e);
          }
      }
docs: Import Properties from a Properties-File as default, if the key is
  already existing, the default will be replaced with the new default.
  
  @param _url Complete Path/Name of the property file to import