The best way to avoid Java JRE update notifications or auto-update on the clients and to control the installed JAVA JRE version is to use (install) a specific version that has the Auto-Update mechanism turned off.
For more information please see following documents:
All Java SE Downloads on MOS (Doc ID 1439822.1)
Support Note: Java Auto-Update (AU) Policy Change (Doc ID 1470691.1)
In your specific case, you will have to install (use) on the clients the Oracle JRE 7 Update 21 with Auto Update Off.
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I was under the impression that this version of JAVA turning the auto-updater off did not do anything.
Also I cannot get to either doc referenced.
From warpstalker about 1/3 down