Cause
This error occurs if you attempt to define a non-mapping method with the same name as an existing property.
Action
Perform one of the following actions.
If you intend the method to be a mapping method, change the method header to conform to the method signature required for mapping methods. This signature is as follows.
methodName(set: Boolean; _value: property-type io) mapping;
If you do not intend the method to be a mapping method, rename the method (by deleting and adding it again) so that it does not have the same name as an existing property.
Delete or rename the existing property.