GrailsParameterMap: params['identifier'] and params['request'] resolve to bean properties instead of map entries on Groovy 5

[sbglasius]

Expected Behavior

Subscript and dot access on a GrailsParameterMap always address a request parameter:

def params = new GrailsParameterMap(request)
params['identifier'] = 'id1'
assert params['identifier'] == 'id1'

getIdentifier() and getRequest() remain reachable as explicit method calls, with params.getIdentifier() returning the id entry of the map — unchanged.

Actual Behaviour

On Groovy 5 (reproduced on 5.0.6 and 5.1.0) the assignment throws:

groovy.lang.ReadOnlyPropertyException: Cannot set read-only property: identifier for class: grails.web.servlet.mvc.GrailsParameterMap
	at groovy.lang.MetaClassImpl.setProperty(MetaClassImpl.java:2837)
	at org.codehaus.groovy.runtime.InvokerHelper.setProperty(InvokerHelper.java:187)
	at org.codehaus.groovy.runtime.DefaultGroovyMethods.putAt(DefaultGroovyMethods.java:12191)

Groovy 5 changed runtime method selection for classes implementing Map: for a String key, DefaultGroovyMethods.putAt(Object, String, Object) (→ setProperty) is now preferred over putAt(Map, K, V) (→ put), and getAt(Object, String) (→ getProperty) over getAt(Map, Object). Because GrailsParameterMap declares getIdentifier() and getRequest() with no setters, those names became read-only properties rather than ordinary map keys.

Expression	Groovy 4.0.30	Groovy 5.x
params['identifier'] = 'x'	map put	throws ReadOnlyPropertyException
params['request'] = 'x'	map put	throws ReadOnlyPropertyException
params['identifier']	map value	getIdentifier() → params.id
params['request']	map value	the HttpServletRequest
params.identifier / params.request	map value	getter result

A request parameter named identifier or request is therefore silently unreachable, and writing one throws. GroovyPageAttributes is affected the same way through the shared base grails.util.AbstractTypeConvertingMap — attrs['gspTagSyntaxCall'] = x writes the field instead of the map.

Steps To Reproduce

1. new GrailsParameterMap(new MockHttpServletRequest())
2. map['identifier'] = 'id1'
3. ReadOnlyPropertyException is thrown.

Added as grails.web.servlet.mvc.GrailsParameterMapTests#testAddingIdentifierParam.

Environment Information

• Grails: 8.0.0-SNAPSHOT (8.0.x)
• Groovy: 5.1.0 (also reproduced on 5.0.6; works on 4.0.30)
• JDK: 21+

Only 8.0.x is affected — 7.0.x is on Groovy 4.x.