code: public long getLong(String propertyName, long defaultValue) {
          Object obj = get(propertyName);
          return obj != null ? ((Number) get(propertyName)).longValue() : defaultValue;
      }
docs: Gets the value of the property as a {@code long} using a default value.
  
  @param propertyName  the property name, not empty
  @param defaultValue  the default value for null or invalid property
  @return the value of the property
  @throws ClassCastException if the value is not compatible