code: private static String getProperty(Properties extensionProperties, String propertyName) {
          if (extensionProperties.containsKey(propertyName)) {
              Object value = extensionProperties.get(propertyName);
              if (value != null) {
                  return value.toString();
              }
          }
  
          return null;
      }
docs: Try to read property from property set. When not set or null value return null else
  return String representation of value object.
  @param extensionProperties
  @param propertyName
  @return