diff --git a/app/src/main/java/info/nightscout/androidaps/interfaces/ConstraintsInterface.java b/app/src/main/java/info/nightscout/androidaps/interfaces/ConstraintsInterface.java
deleted file mode 100644
index 14b2d549af..0000000000
--- a/app/src/main/java/info/nightscout/androidaps/interfaces/ConstraintsInterface.java
+++ /dev/null
@@ -1,66 +0,0 @@
-package info.nightscout.androidaps.interfaces;
-
-import info.nightscout.androidaps.data.Profile;
-
-/**
- * Created by mike on 15.06.2016.
- */
-public interface ConstraintsInterface {
-
-    default Constraint<Boolean> isLoopInvocationAllowed(Constraint<Boolean> value) {
-        return value;
-    }
-
-    default Constraint<Boolean> isClosedLoopAllowed(Constraint<Boolean> value) {
-        return value;
-    }
-
-    default Constraint<Boolean> isAutosensModeEnabled(Constraint<Boolean> value) {
-        return value;
-    }
-
-    default Constraint<Boolean> isAMAModeEnabled(Constraint<Boolean> value) {
-        return value;
-    }
-
-    default Constraint<Boolean> isSMBModeEnabled(Constraint<Boolean> value) {
-        return value;
-    }
-
-    default Constraint<Boolean> isUAMEnabled(Constraint<Boolean> value) {
-        return value;
-    }
-
-    default Constraint<Boolean> isAdvancedFilteringEnabled(Constraint<Boolean> value) {
-        return value;
-    }
-
-    default Constraint<Boolean> isSuperBolusEnabled(Constraint<Boolean> value) {
-        return value;
-    }
-
-    default Constraint<Double> applyBasalConstraints(Constraint<Double> absoluteRate, Profile profile) {
-        return absoluteRate;
-    }
-
-    default Constraint<Integer> applyBasalPercentConstraints(Constraint<Integer> percentRate, Profile profile) {
-        return percentRate;
-    }
-
-    default Constraint<Double>  applyBolusConstraints(Constraint<Double>  insulin) {
-        return insulin;
-    }
-
-    default Constraint<Double>  applyExtendedBolusConstraints(Constraint<Double>  insulin) {
-        return insulin;
-    }
-
-    default Constraint<Integer> applyCarbsConstraints(Constraint<Integer> carbs) {
-        return carbs;
-    }
-
-    default Constraint<Double> applyMaxIOBConstraints(Constraint<Double> maxIob) {
-        return maxIob;
-    }
-
-}
diff --git a/app/src/main/java/info/nightscout/androidaps/interfaces/ConstraintsInterface.kt b/app/src/main/java/info/nightscout/androidaps/interfaces/ConstraintsInterface.kt
new file mode 100644
index 0000000000..0634bbb139
--- /dev/null
+++ b/app/src/main/java/info/nightscout/androidaps/interfaces/ConstraintsInterface.kt
@@ -0,0 +1,79 @@
+package info.nightscout.androidaps.interfaces
+
+import info.nightscout.androidaps.data.Profile
+
+/**
+ * Created by mike on 15.06.2016.
+ */
+interface ConstraintsInterface {
+
+    @JvmDefault
+    fun isLoopInvocationAllowed(value: Constraint<Boolean>): Constraint<Boolean> {
+        return value
+    }
+
+    @JvmDefault
+    fun isClosedLoopAllowed(value: Constraint<Boolean>): Constraint<Boolean> {
+        return value
+    }
+
+    @JvmDefault
+    fun isAutosensModeEnabled(value: Constraint<Boolean>): Constraint<Boolean> {
+        return value
+    }
+
+    @JvmDefault
+    fun isAMAModeEnabled(value: Constraint<Boolean>): Constraint<Boolean> {
+        return value
+    }
+
+    @JvmDefault
+    fun isSMBModeEnabled(value: Constraint<Boolean>): Constraint<Boolean> {
+        return value
+    }
+
+    @JvmDefault
+    fun isUAMEnabled(value: Constraint<Boolean>): Constraint<Boolean> {
+        return value
+    }
+
+    @JvmDefault
+    fun isAdvancedFilteringEnabled(value: Constraint<Boolean>): Constraint<Boolean> {
+        return value
+    }
+
+    @JvmDefault
+    fun isSuperBolusEnabled(value: Constraint<Boolean>): Constraint<Boolean> {
+        return value
+    }
+
+    @JvmDefault
+    fun applyBasalConstraints(absoluteRate: Constraint<Double>, profile: Profile): Constraint<Double> {
+        return absoluteRate
+    }
+
+    @JvmDefault
+    fun applyBasalPercentConstraints(percentRate: Constraint<Int>, profile: Profile): Constraint<Int> {
+        return percentRate
+    }
+
+    @JvmDefault
+    fun applyBolusConstraints(insulin: Constraint<Double>): Constraint<Double> {
+        return insulin
+    }
+
+    @JvmDefault
+    fun applyExtendedBolusConstraints(insulin: Constraint<Double>): Constraint<Double> {
+        return insulin
+    }
+
+    @JvmDefault
+    fun applyCarbsConstraints(carbs: Constraint<Int>): Constraint<Int> {
+        return carbs
+    }
+
+    @JvmDefault
+    fun applyMaxIOBConstraints(maxIob: Constraint<Double>): Constraint<Double> {
+        return maxIob
+    }
+}
\ No newline at end of file
diff --git a/build.gradle b/build.gradle
index 3327014f1f..520a0dfa18 100644
--- a/build.gradle
+++ b/build.gradle
@@ -34,6 +34,13 @@ allprojects {
             }
         }
     }
+    //Support @JvmDefault
+    tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
+        kotlinOptions {
+            freeCompilerArgs = ['-Xjvm-default=enable'] //enable or compatibility
+            jvmTarget = "1.8"
+        }
+    }
 }
 
 task clean(type: Delete) {