Fixes #4928

There are two different bugs here, but I decided to include them in one issue/PR since the fix for both is quite simple and they are related.

Problem 1

In Java < 1.4, assert is not yet a keyword and can therefore be used as a regular identifier. There is an ambiguity in the grammar that causes a parse error when attempting to parse the statement:

assert++;

It is very unlikely that any JavaParser user would encounter this error in practice given the fact that this is only valid code for Java 1-3, but I don't see any potential negative consequences for the fix.

The parser currently tries to parse this as an assert statement followed by a PREFIX_INCREMENT UnaryExpr. Parsing the UnaryExpr then fails since there is no expression following the ++.

This is fixed by adding a lookahead for the assert statement to check whether the ++ is followed by an expression or not.

Problem 2

module is a conditional keyword that can still be used as a package name. #4910 introduced a new grammar ambiguity causing a parse error when attempting to parse an import statement for a package starting with module:

import module.Foo

The parser attempts to parse this as a module import import module .Foo and crashes when attempting to parse the name since a name cannot start with ..

The fix is to consider two cases separately:

• either there is a module token followed by a name
• or there is just a name

Once these are separate cases, a lookahead can be used to figure out which of these should be applied