code: private Map<String, Object> getProperties(GDLParser.PropertiesContext propertiesContext) {
      if (propertiesContext != null) {
        Map<String, Object> properties = new HashMap<>();
        for (GDLParser.PropertyContext property : propertiesContext.property()) {
          properties.put(property.Identifier().getText(), getPropertyValue(property.literal()));
        }
        return properties;
      }
      return Collections.emptyMap();
    }
docs: Returns the properties map from a given properties context.
  
  @param propertiesContext properties context
  @return properties map or {@code null} if context was null