code: function (fieldDefinition, fieldTypePropertyName, propertyName) {
  		let severity = fieldDefinition.severity;
  
  		if (typeof fieldDefinition.fieldType === 'object') {
  
  			if (fieldDefinition.fieldType.hasOwnProperty('severity')) {
  				// If the field type has an own severity, take this one.
  				severity = fieldDefinition.fieldType.severity;
  			}
  
  			if (fieldTypePropertyName) {
  				if (fieldDefinition.fieldType[fieldTypePropertyName]) {
  					if (fieldDefinition.fieldType[fieldTypePropertyName].hasOwnProperty('severity')) {
  						// But if the check in the field type also has an own severity, then this one will be taken
  						severity = fieldDefinition.fieldType[fieldTypePropertyName].severity;
  					}
  				}
  			}
  		}
  
  		if (propertyName) {
  			// in this case there is a sibling property line 'mandatory' which also could have an own severity.
  			if (typeof fieldDefinition[propertyName] === 'object') {
  				if (fieldDefinition[propertyName].hasOwnProperty('severity')) {
  					severity = fieldDefinition[propertyName].severity;
  				}
  			}
  		}
  
  		return severity;
  	}
docs: Returns the severity for a check property. The severity may be defined globaly
  for the complete field, but also may be defined on a per check basis
  @param fieldDefinition The field_definition
  @param fieldTypePropertyName The name of the property. This property is under the fieldType
  @param propertyName The name of the property. This property is a sibling of fieldType
  
  Only one of the property names should be given