Fix cascading generic types (#393)

Author: SentryMan

jsonb-generator/src/main/java/io/avaje/jsonb/generator/FieldProperty.java

@@ -207,7 +207,7 @@ void cascadeTypes(Set<String> types) {
       } else if ("java.util.Map".equals(topType)) {
         types.add(genericType.firstParamType());
         types.add(genericType.secondParamType());
-      } else {
+      } else if (!GenericType.isGeneric(rawType)) {
         types.add(topType);
       }
     }

jsonb-generator/src/test/java/io/avaje/jsonb/generator/models/valid/GenericCascade.java

@@ -0,0 +1,21 @@
+package io.avaje.jsonb.generator.models.valid;
+
+import io.avaje.jsonb.Json;
+
+@Json
+public class GenericCascade {
+  private GenericType<String> list;
+
+  public GenericType<String> getList() {
+    return list;
+  }
+
+  public void setList(GenericType<String> list) {
+    this.list = list;
+  }
+
+  static class GenericType<T> {
+
+    public T field;
+  }
+}