Java9 Grammar doesn't properly handle nested typeArguments within unannClassType

[mattkindy]

As an example,

Map<String, Class<?>>

will cause an error, while

Map<String, Class<?> >

is handled properly.

[mattkindy]

Think the reason this is happening is greedy checks on the following:

shiftExpression
    :    additiveExpression
    |    shiftExpression '<<' additiveExpression
    |    shiftExpression '>>' additiveExpression
    |    shiftExpression '>>>' additiveExpression
    ;

These tokens are implicit during lexing and have match priority. The solution is probably

shiftExpression
    :    additiveExpression
    |    shiftExpression '<' '<' additiveExpression
    |    shiftExpression '>' '>' additiveExpression
    |    shiftExpression '>' '>' '>' additiveExpression
    ;

As another note, this seems to have happened when the Java9 grammar was made to support shiftExpression since the Java8 grammar here seems to lack them. When shift tokens were commented out, it didn't cause errors because they weren't used in the parser rules. In general, the parser rules should not use string literals. I would prefer

shiftExpression
    :    additiveExpression
    |    shiftExpression LT LT additiveExpression
    |    shiftExpression GT GT additiveExpression
    |    shiftExpression GT GT GT additiveExpression
    ;