protected void firePropertyChange(final String propertyName, final Object oldVal, final Object newVal) {
    propertySupport.firePropertyChange(propertyName, oldVal, newVal);
  }
Send property change notification to attached listeners.

@param propertyName property name.
@param oldVal       old value.
@param newVal       new value.
olv-core/src/main/java/pl/otros/logview/accept/query/org/apache/log4j/rule/AbstractRule.java