Without specific handling for maps in `javaTypeLiteralSuffixFor`,
no literal suffix was ever appended, resulting in compilation error in
the validator for constraints on (Java) long, float or double. This
commit mimics the structure of `javaTypeFor` to infer the suffix based
on whether keys or values are targeted.

Signed-off-by: Brice Jaglin <bjaglin@teads.tv>

Co-authored-by: Ryan Michela <rmichela@salesforce.com>