remove NotNullValidator

common/src/main/java/com/dfsek/terra/api/transform/NotNullValidator.java

@@ -1,8 +0,0 @@
-package com.dfsek.terra.api.transform;
-
-public class NotNullValidator<T> implements Validator<T> {
-    @Override
-    public boolean validate(T value) {
-        return !(value == null);
-    }
-}

common/src/main/java/com/dfsek/terra/api/transform/Validator.java

@@ -1,6 +1,12 @@
 package com.dfsek.terra.api.transform;
 
 
+import java.util.Objects;
+
 public interface Validator<T> {
     boolean validate(T value) throws TransformException;
+
+    static <T> Validator<T> notNull() {
+        return Objects::nonNull;
+    }
 }