Fix enum field update

[liuzhengyang]

The name of the static field in Enum class is "$VALUES" instead of "ENUM$VALUES".

By the way, i can't run tests ClassInitTest, it throws exception throw new IllegalStateException("Plugin manager is not correctly initialized , maybe because of junit running order or other issue.
But i have tested this change by some tricky methods.

[skybber]

What java version / compiler are you using?

[liuzhengyang]

What java version / compiler are you using?

Java8 and Java11

[skybber]

It looks that there is no standard for the name of enum field. I've checked output of different java compilers using javap -p CheckedEnum.class and Eclipse JDT uses ENUM$VALUES; , javac uses $VALUES;. Better solution should check both versions. Could you please modify PR?

[liuzhengyang]

I have modified PR.
First check field type is array, then check field name start with $VALUES or ENUM$VALUES.
Because when that name clash with enum field name, javac append $ $$ and eclipse compiler append _0 _1

[skybber]

Looks great, thanks!