If you have an enum such as this
    enum Test {FOO, BAR}
and you call
    Enum.valueOf(Test.class, "BAZ")
then you get this exception:
    java.lang.IllegalArgumentException: No enum const class Test.BAZ
The word "class" is spurious and confusing. The code that throws the exception:
    throw new IllegalArgumentException("No enum const " + enumType +"." + name);
should say enumType.getName() because Class.toString() includes the word "class" in its output.

Also, abbreviating "constant" to "const" seems a bit gratuitous.