backport OAK-7511 (nullability annotations) to 1.8

ERROR: Bundle org.apache.jackrabbit.jackrabbit-api [23] Error starting file:/C:/tmp/1532702976390-0/bundles/org.apache.jackrabbit.jackrabbit-api_2.16.2.jar (org.osgi.framework.BundleException: Unable to resolve org.apache.jackrabbit.jackrabbit-api [23](R 23.0): missing requirement [org.apache.jackrabbit.jackrabbit-api [23](R 23.0)] osgi.wiring.package; (osgi.wiring.package=javax.annotation) Unresolved requirements: [[org.apache.jackrabbit.jackrabbit-api [23](R 23.0)] osgi.wiring.package; (osgi.wiring.package=javax.annotation)])
org.osgi.framework.BundleException: Unable to resolve org.apache.jackrabbit.jackrabbit-api [23](R 23.0): missing requirement [org.apache.jackrabbit.jackrabbit-api [23](R 23.0)] osgi.wiring.package; (osgi.wiring.package=javax.annotation) Unresolved requirements: [[org.apache.jackrabbit.jackrabbit-api [23](R 23.0)] osgi.wiring.package; (osgi.wiring.package=javax.annotation)]
        at org.apache.felix.framework.Felix.resolveBundleRevision(Felix.java:4149)
        at org.apache.felix.framework.Felix.startBundle(Felix.java:2119)
        at org.apache.felix.framework.Felix.setActiveStartLevel(Felix.java:1373)
        at org.apache.felix.framework.FrameworkStartLevelImpl.run(FrameworkStartLevelImpl.java:308)
        at java.base/java.lang.Thread.run(Thread.java:834)