Full support for OpenJDK

[tfr42]

As of the Java 8/11 release Oracle Inc. has changed it's license terms with regards the usage of Oracle JDK in productions systems. The TMC has the motion to fully move to OpenJDK and do not rely on Oracle JDK builds anymore.

Recommended reading:

• https://www.azul.com/what-comes-after-jdk-8/
• https://medium.com/criciumadev/its-time-migrating-to-java-11-5eb3868354f9
• https://dev.karakun.com/java/2018/06/25/java-releases.html
• https://adoptopenjdk.net/
• https://github.com/deegree/deegree3/wiki/End-of-Life-and-Support-Matrix

[tfr42]

The wiki page https://github.com/deegree/deegree3/wiki/Java-SE-11-Support explains also why we favor OpenJDK for future releases of deegree webservices.

[tfr42]

The full support for OpenJDK is planned for deegree webservices 3.5 line when moving to Java SE 11, see #857 for more information.

[tfr42]

For JDK 8 the support for OpenJDK 8 is done. The master branch and all open pull requests are build using AdoptOpenJDK 8 and/or Amazon Corretto JDK 8 (see issue #1074 for more information which versions are used).
Oracle JDK 8 is not longer used to compile, run or test deegree web services on our build infrastructure (see #1077 and https://github.com/deegree/deegree3/wiki/Infrastructure for more information about the infrastructure).