fix: do not obfuscate OptionalStateRules

build.gradle.kts

@@ -6,6 +6,6 @@ plugins {
 }
 
 allprojects {
-    version = "0.3.0"
+    version = "0.3.1"
     group = "de.thetadev.formconductor"
 }

compose-ui/consumer-rules.pro

@@ -1,4 +1,6 @@
--keepclassmembers class * extends de.thetadev.formconductor.validation.rules.ValidationRule {
+# Keep custom validaton rules
+-keep class * extends de.thetadev.formconductor.validation.rules.ValidationRule {
+    public static ** INSTANCE;
     <methods>;
     public static <fields>;
 }

core/src/main/java/de/thetadev/formconductor/validation/rules/OptionalStateRule.kt

@@ -1,5 +1,5 @@
 package de.thetadev.formconductor.validation.rules
 
-interface OptionalStateRule<T> {
+interface OptionalStateRule<T>: ValidationRule {
     fun isOptional(state: T): Boolean
 }