Enum displayer cannot be used on wiki macro parameter

Reproduction step:

• Create a wiki macro with a parameter whom type is an enum
• Try to use that macro in a document

Expected result:

• a select is created when using the macro with the enum values

Obtained result:

• a select is created but without any value in it and the following warning appears:

  2020-05-13 14:09:04,201 [http://localhost:8080/xwiki/bin/get/CKEditor/MacroService?outputSyntax=plain&language=en&data=descriptor&macroId=test1%2Fxwiki%2F2.1] WARN  o.x.v.i.DefaultVelocityEngine  - Cannot retrieve method getEnumConstants from object of class java.lang.Class due to security restrictions. 
  2020-05-13 14:09:04,202 [http://localhost:8080/xwiki/bin/get/CKEditor/MacroService?outputSyntax=plain&language=en&data=descriptor&macroId=test1%2Fxwiki%2F2.1] WARN  o.x.v.i.DefaultVelocityEngine  - Cannot retrieve method getEnumConstants from object of class java.lang.Class due to security restrictions. 
  

Note: in order to ease the reproduction, you can directly import the attached XAR and try to use the macro "test1".