Re-enable Null analysis in Maven (#3973)

Signed-off-by: Stefan Triller <stefan.triller@telekom.de>

pom.xml

@@ -50,6 +50,7 @@
     <xtext-version>2.9.2</xtext-version>
     <karaf.version>4.0.3</karaf.version>
     <ds-annotations.version>1.2.8</ds-annotations.version>
+    <jdt-annotations.version>2.1.0</jdt-annotations.version>
     <build.helper.maven.plugin.version>1.8</build.helper.maven.plugin.version>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   </properties>
@@ -156,10 +157,15 @@
                 <artifactId>org.apache.felix.scr.ds-annotations</artifactId>
                 <version>${ds-annotations.version}</version>
               </extraClasspathElement>
+              <extraClasspathElement>
+                <groupId>org.eclipse.jdt</groupId>
+                <artifactId>org.eclipse.jdt.annotation</artifactId>
+                <version>${jdt-annotations.version}</version>
+              </extraClasspathElement>
             </extraClasspathElements>
             <compilerArgs>
-              <arg>-err:-nullAnnot,-null,-syntacticAnalysis</arg>
-              <!--<arg>-warn:+null,+inheritNullAnnot,+nullUncheckedConversion,+nullAnnotRedundant</arg>-->
+              <arg>-err:+nullAnnot(org.eclipse.jdt.annotation.Nullable|org.eclipse.jdt.annotation.NonNull|org.eclipse.jdt.annotation.NonNullByDefault),+inheritNullAnnot</arg>
+              <arg>-warn:+null,+inheritNullAnnot,+nullAnnotConflict,+nullUncheckedConversion,+nullAnnotRedundant,+nullDereference</arg>
             </compilerArgs>
           </configuration>          
         </plugin>