try setting parser version to 2.6.3

build.gradle

@@ -31,7 +31,7 @@ project(':de.prob.core') {
 	}
 
 
-        def parser_version = '2.8.0'
+        def parser_version = '2.6.3'
 
 	dependencies {
 	 compile group: "de.hhu.stups", name: "answerparser", version: parser_version , changing: true

de.prob.core/build.gradle

 apply plugin: 'java'
 
-def parser_version = '2.8.0'
+def parser_version = '2.6.3'
 
 dependencies {
  compile group: "de.hhu.stups", name: "answerparser", version: parser_version , changing: true