I see that Google App Engine apps run on a so-called secured sandbox JRE; that is, a JRE that Google modified and that makes changes to certain JRE types. This is how GAE prevents developers from writing apps that can do things like:

• Access the local file system via File
• Make remote JDBC calls
• Use JNDI
• Lots of other restrictions

We have a similar need where we have an app that developers will be able to write plugins for. These plugins will need to utilize an API (a JAR) that we distribute with our app. We cannot afford for plugins to do certain things, particularly on the end user's file system, and need to modify the File class in a similar manner that GAE does.

Long back-story short, this means we'll need to ship our app with a custom, modified JRE.

My question: is this legal to do, or did Google likely pay Oracle some fee to modify/distribute their own JRE for app engine?