add compile warning for http valid (#672)

Author: SentryMan

http-generator-core/src/main/java/io/avaje/http/generator/core/BaseProcessor.java

@@ -19,7 +19,6 @@
 import javax.annotation.processing.SupportedOptions;
 import javax.lang.model.SourceVersion;
 import javax.lang.model.element.Element;
-import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.Modifier;
 import javax.lang.model.element.TypeElement;
 import javax.lang.model.util.ElementFilter;
@@ -54,11 +53,12 @@ public SourceVersion getSupportedSourceVersion() {
   @Override
   public Set<String> getSupportedAnnotationTypes() {
     return Set.of(
-      PathPrism.PRISM_TYPE,
-      ControllerPrism.PRISM_TYPE,
-      OpenAPIDefinitionPrism.PRISM_TYPE,
-      MappedParamPrism.PRISM_TYPE,
-      MapImportPrism.PRISM_TYPE);
+        PathPrism.PRISM_TYPE,
+        ControllerPrism.PRISM_TYPE,
+        OpenAPIDefinitionPrism.PRISM_TYPE,
+        MappedParamPrism.PRISM_TYPE,
+        MapImportPrism.PRISM_TYPE,
+        HttpValidPrism.PRISM_TYPE);
   }
 
   @Override
@@ -91,7 +91,7 @@ public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment
     if (round.errorRaised()) {
       return false;
     }
-
+    getElements(round, HttpValidPrism.PRISM_TYPE).forEach(this::warnValid);
     for (final var type : ElementFilter.typesIn(getElements(round, MappedParamPrism.PRISM_TYPE))) {
       var prism = MappedParamPrism.getInstanceOn(type);
       registerParamMapping(type, prism.factoryMethod());
@@ -148,6 +148,12 @@ public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment
     return false;
   }
 
+  private void warnValid(Element e) {
+    if (!ControllerPrism.isPresent(e) && !ControllerPrism.isPresent(e.getEnclosingElement())) {
+      logWarn(e, "%s should only be used in Controller Classes", HttpValidPrism.PRISM_TYPE);
+    }
+  }
+
   private Set<? extends Element> getElements(RoundEnvironment round, String name) {
     return Optional.ofNullable(typeElement(name))
       .map(round::getElementsAnnotatedWith)