* Replicate java_multiple_files bug in ReflectiveValidatorIndex

Signed-off-by: Ryan Michela <rmichela@salesforce.com>

* Generate exploded java validator classes when java_multiple_files=true

Signed-off-by: Ryan Michela <rmichela@salesforce.com>

* Fix bazel build

Signed-off-by: Ryan Michela <rmichela@salesforce.com>