Starting with version 1.0.0 : Java 11 should be used for building (maven.compiler.release can still be set to java 8)

[mttfranci]

To comply with some test time libraries (for instnace hsqldb) library should be built with java11.
It is still possibile to use java 1.8 (8) as compliance level, for instance :

            <java-version-compliance>8</java-version-compliance>
	    <maven.compiler.source>${java-version-compliance}</maven.compiler.source>
	    <maven.compiler.target>${java-version-compliance}</maven.compiler.target>	
	    <maven.compiler.release>${java-version-compliance}</maven.compiler.release>