Issue type for wrong enum value types

[javagl]

A low-level detail, rather an internal note:

When there is an enum definition like

        "exampleEnum": {
          "type": "string",
          "enum": [
            "VALUE_A",
            "VALUE_B"
          ]

and the JSON input contains something like
exampleEnum: 12345
then this is reported as
VALUE_NOT_IN_LIST: The 'exampleEnum' property has the value 12345, but must be one of VALUE_A,VALUE_B

This is correct and reasonable.

One could make a case that this should be reported as a
TYPE_MISMATCH: The 'exampleEnum' property must have type 'string', but has type 'number'

But I think that this is a special case, where the type itself does not matter so much, and the details (i.e. the allowed values) add valuable information that justify using the more specific VALUE_NOT_IN_LIST issue.