Update unclear Fragment Javadoc.
Update unclear Fragment Javadoc.

"Empty" could imply that the constructor body itself is empty, which
is not a requirement. All that matters is that the constructor is
public and takes no arguments.

Change-Id: Id1cda8835baee9f9ad89aba8b3d33b963e61e718

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base