This is because, there is an Entry during the installation
Solution:
Remove line MIDDLEWARE\JDK from file INVENTORY.XML which is located in
C:\PROGRAM FILES\ORACLE\INVENTORY\CONTEXTSXML\INVENTORY.XML
Save the file and restart installation of OEM 12c
Solution:
Remove line MIDDLEWARE\JDK from file INVENTORY.XML which is located in
C:\PROGRAM FILES\ORACLE\INVENTORY\CONTEXTSXML\INVENTORY.XML
Save the file and restart installation of OEM 12c