Change exception message to include given input parameter value (#653)

* Change exception message

* Change exception type

src/Altinn.Authorization.ABAC/Utils/XacmlJsonXmlConverter.cs

@@ -219,7 +219,7 @@ private static string ConvertDataType(XacmlJsonAttribute jsonAttribute)
                 case XacmlConstants.DataTypes.XMLInteger:
                     return XacmlConstants.DataTypes.XMLInteger;
                 default:
-                    throw new Exception("Not supported");
+                    throw new ArgumentException($"Given data type; {jsonAttribute.DataType}, is not supported.", nameof(jsonAttribute));
             }
         }
     }