JavaBeanExecutable fails to initialize for enum type

Original issue reported in https://github.com/quarkusio/quarkus/issues/3284
The problem is caused by enum constructor been processed by `JavaBeanExecutable`. Two arguments are added to enum constructors (int and string). Both of which are returning `false` for `isSynthetic()` and `isImplicit()` calls. At the same time the `executable.getGenericParameterTypes()` is empty.