clang-format: [Java] Improve generic return type formatting.

Before:
  public<R> ArrayList<R> get() {

After:
  public <R> ArrayList<R> get() {

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@221979 91177308-0d34-0410-b5e6-96231b3b80d8