diff --git a/li.strolch.model/src/main/java/li/strolch/model/json/FromFlatJsonVisitor.java b/li.strolch.model/src/main/java/li/strolch/model/json/FromFlatJsonVisitor.java
index 03a970108..3d02707f1 100644
--- a/li.strolch.model/src/main/java/li/strolch/model/json/FromFlatJsonVisitor.java
+++ b/li.strolch.model/src/main/java/li/strolch/model/json/FromFlatJsonVisitor.java
@@ -15,23 +15,23 @@ import li.strolch.utils.collections.MapOfSets;
 /**
  * <p>
  * Maps a given {@link JsonObject} to a {@link StrolchRootElement}. All {@link Parameter Parameters} on the element are
- * iterated expected to be found as a member on the {@link JsonObject}.
+ * iterated and expected to be found as a member on the {@link JsonObject}.
  * </p>
  * 
  * <p>
- * To not map a {@link Parameter} add it to the {@link MapOfSets}, to ignore a whole {@link ParameterBag} then add an
- * empty set with the bag id.
+ * To ignore {@link Parameter Parameters} or {@link ParameterBag ParameterBags} use the
+ * {@link #ignoreParameter(String, String)} and {@link #ignoreBag(String)} methods
  * </p>
  * 
  * <p>
- * Optional values are handled similar, but only a parameter can be optional, not a whole bag
+ * {@link Parameter} can be made optional by using the {@link #optionalParameter(String, String)} method
  * </p>
  * 
  * @author Robert von Burg <eitch@eitchnet.ch>
  *
  * @param <T>
  */
-public class FromFlatJsonVisitor<T extends StrolchRootElement> {
+public class FromFlatJsonVisitor {
 
 	private MapOfSets<String, String> ignoredKeys;
 	private MapOfSets<String, String> optionalKeys;
@@ -58,7 +58,7 @@ public class FromFlatJsonVisitor<T extends StrolchRootElement> {
 		this.optionalKeys.addElement(bagId, paramId);
 	}
 
-	public void visit(T element, JsonObject jsonObject) {
+	public void visit(StrolchRootElement element, JsonObject jsonObject) {
 
 		Set<String> bagKeySet = element.getParameterBagKeySet();
 		for (String bagId : bagKeySet) {
diff --git a/li.strolch.model/src/main/java/li/strolch/model/json/ToFlatJsonVisitor.java b/li.strolch.model/src/main/java/li/strolch/model/json/ToFlatJsonVisitor.java
index 30185ccd2..e7965d8ca 100644
--- a/li.strolch.model/src/main/java/li/strolch/model/json/ToFlatJsonVisitor.java
+++ b/li.strolch.model/src/main/java/li/strolch/model/json/ToFlatJsonVisitor.java
@@ -21,14 +21,24 @@ import li.strolch.utils.collections.MapOfSets;
 /**
  * <p>
  * Maps a given {@link StrolchRootElement} to a {@link JsonObject}. All {@link Parameter Parameters} are mapped to a
- * member of the {@link JsonObject}.
+ * member of the {@link JsonObject}, {@link ParameterBag ParameterBags} are thus removed
  * </p>
  * 
  * <p>
- * To not map a {@link Parameter} add it to the {@link MapOfSets}, to ignore a whole {@link ParameterBag} then add an
- * empty set with the bag id.
+ * To ignore {@link Parameter Parameters} or {@link ParameterBag ParameterBags} use the
+ * {@link #ignoreParameter(String, String)} and {@link #ignoreBag(String)} methods
  * </p>
  * 
+ * <p>
+ * The mapping can be extended by setting hook:
+ * </p>
+ * 
+ * <pre>
+ * visitor.setHook((element, jsonObject) -> {
+ * 	// do work
+ * });
+ * </pre>
+ * 
  * @author Robert von Burg <eitch@eitchnet.ch>
  */
 public class ToFlatJsonVisitor<T extends StrolchRootElement> {
diff --git a/li.strolch.rest/src/main/java/li/strolch/rest/util/JsonServiceArgument.java b/li.strolch.rest/src/main/java/li/strolch/rest/util/JsonServiceArgument.java
index d534b8516..19289d430 100644
--- a/li.strolch.rest/src/main/java/li/strolch/rest/util/JsonServiceArgument.java
+++ b/li.strolch.rest/src/main/java/li/strolch/rest/util/JsonServiceArgument.java
@@ -13,7 +13,14 @@ import li.strolch.service.api.ServiceArgument;
  */
 public class JsonServiceArgument extends ServiceArgument {
 	private static final long serialVersionUID = 1L;
-	public String baseUrl;
+	
+	/**
+	 * the objectId - its context is defined by the service 
+	 */
 	public String objectId;
+	
+	/**
+	 * The input object
+	 */
 	public JsonElement jsonElement;
 }