Support Java 9+

[sknop]

The current project does not compile with Java 10. It is the Maven plugin-in in particular that fails:

[INFO] avro-schema-editor-parent .......................... SUCCESS [ 0.124 s]
[INFO] org.talend.avro.schema.editor ...................... FAILURE [ 14.867 s]
[INFO] org.talend.avro.schema.editor.feature .............. SKIPPED
[INFO] org.talend.avro.schema.editor.repository ........... SKIPPED
[INFO] Talend Avro Schema Editor POC 0.0.1-SNAPSHOT ....... SKIPPED
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 02:11 min
[INFO] Finished at: 2018-09-18T18:06:05+01:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.eclipse.tycho:tycho-compiler-plugin:1.0.0:compile (default-compile) on project org.talend.avro.schema.editor: Compilation failure: Compilation failure:
[ERROR] /Users/myuser/git/avro-schema-editor/org.talend.avro.schema.editor/src/org/talend/avro/schema/editor/edit/handlers/AddElementPropertyTester.java:[1]
[ERROR] package org.talend.avro.schema.editor.edit.handlers;
[ERROR] ^
[ERROR] The type java.lang.Object cannot be resolved. It is indirectly referenced from required .class files

[timbault]

It is planned to move soon to Java 11.