Update Transaction API getCommittedVersion To Avoid Autoboxing

[belugabehr]

The Long getCommittedVersion() has an overhead of Autoboxing the primitive long value to a Long object. It's not clear to me the use case for this return value - the JavaDoc do not comment on what a 'null' value returned would indicate.

foundationdb/bindings/java/src/main/com/apple/foundationdb/Transaction.java

Lines 244 to 254 in 280b10f

	/**
	* Gets the version number at which a successful commit modified the database.
	* This must be called only after the successful (non-error) completion of a call
	* to {@link #commit()} on this {@code Transaction}, or the behavior is undefined.
	* Read-only transactions do not modify the database when committed and will have
	* a committed version of -1. Keep in mind that a transaction which reads keys and
	* then sets them to their current values may be optimized to a read-only transaction.
	*
	* @return the database version at which the commit succeeded
	*/
	Long getCommittedVersion();

It looks like the source for this data is primitive already:

foundationdb/bindings/java/src/main/com/apple/foundationdb/FDBTransaction.java

Line 648 in 280b10f

return Transaction_getCommittedVersion(getPtr());

Please consider adding a new method with a primitive return type to avoid this overhead.

I happened to come across this when reviewing an application that had churned 9GB of Long values in heap in ~30min - certainly not the end of the world, but something to flag. Thanks.