EBS has lots of versions like 11.5.9, 11.5.10, 12 etc. Developer should use the correct version of JDeveloper with OAF extension. When you create extensions or customize EBS OA Framework pages, you must use the version of JDeveloper shipped by the EBS product team. The version of JDeveloper is specific to the ATG patch level, so there is a new version of JDeveloper for each release of ATG patch-set.
To determine which patch to use, you can check the framework version in your instance by using http://(host):(port)
For Example if the instance base URL is http://vis.oracle.com:8080/ then type http://vis.oracle.com:8080/OA_HTML/OAInfo.jsp. Note down OA Framework Version. Go to Metalink Note 416708.1, find out the JDeveloper patch matching with OAF version and download. Unzip the downloaded file.
We can also find useful informations in metalink.oracle.com.