GROOVY-8529: InvocationWriter also needs fix for calling static interface methods (fix test target bytecode version)
diff --git a/subprojects/tests-vm8/build.gradle b/subprojects/tests-vm8/build.gradle
index 82c9330..9569173 100644
--- a/subprojects/tests-vm8/build.gradle
+++ b/subprojects/tests-vm8/build.gradle
@@ -26,6 +26,11 @@
     targetCompatibility = 1.8
 }
 
+tasks.withType(GroovyCompile) {
+    sourceCompatibility = 1.8
+    targetCompatibility = 1.8
+}
+
 sourceSets {
     test {
         java {