update test/readme

re #158 (comment)

README.md

@@ -226,7 +226,11 @@ g.V.has(age).order(By(age, Order.decr))
 More working examples in [TraversalSpec](https://github.com/mpollmeier/gremlin-scala/blob/master/gremlin-scala/src/test/scala/gremlin/scala/TraversalSpec.scala).
 
 ### Mapping vertices from/to case classes
-You can save and load case classes as a vertex - implemented with a [blackbox macro](http://docs.scala-lang.org/overviews/macros/blackbox-whitebox.html). You can optionally annotate the id and label of your case class. Scala's `Option` types will be automatically unwrapped, i.e. a `Some[A]` will be stored as the value of type `A` in the database, or `null` if it's `None`. If we wouldn't unwrap it, the database would have to understand Scala's Option type itself. The same goes for value classes, i.e. a `case class ShoeSize(value: Int) extends AnyVal` will be stored as an Integer. Note: your classes must be defined outside the scope where they are being used (e.g. in the code below the class `Example` cannot be inside `object Main`). 
+You can save and load case classes as a vertex - implemented with a [blackbox macro](http://docs.scala-lang.org/overviews/macros/blackbox-whitebox.html). You can optionally annotate the id and label of your case class. Scala's `Option` types will be automatically unwrapped, i.e. a `Some[A]` will be stored as the value of type `A` in the database, or `null` if it's `None`. If we wouldn't unwrap it, the database would have to understand Scala's Option type itself. The same goes for value classes, i.e. a `case class ShoeSize(value: Int) extends AnyVal` will be stored as an Integer. 
+
+Note: your classes must be defined outside the scope where they are being used (e.g. in the code below the class `Example` cannot be inside `object Main`). 
+
+Note: you cannot specify the id when adding a vertex like this. Using `@id` only works when retrieving the vertex back from the graph.
 
 ```scala
 // this does _not_ work in a REPL

gremlin-scala/src/test/scala/gremlin/scala/MarshallableSpec.scala

@@ -20,9 +20,8 @@ case class CCWithOptionIdNested(s: String, @id id: Option[Int], i: MyValueClass)
 case class CCWithLabel(s: String)
 
 @label("the_label")
-case class CCWithLabelAndId(
+case class ComplexCC(
     s: String,
-    @id id: Int,
     l: Long,
     o: Option[String],
     seq: Seq[String],
@@ -125,26 +124,25 @@ class MarshallableSpec extends WordSpec with Matchers {
     }
 
     "use @label and @id annotations" in new Fixture {
-      val ccWithLabelAndId = CCWithLabelAndId(
+      val cc = ComplexCC(
         "some string",
-        id = Int.MaxValue,
         Long.MaxValue,
         Some("option type"),
         Seq("test1", "test2"),
         Map("key1" -> "value1", "key2" -> "value2"),
         NestedClass("nested")
       )
 
-      val v = graph + ccWithLabelAndId
+      val v = graph + cc
 
       val vl = graph.V(v.id).head
       vl.label shouldBe "the_label"
-      vl.valueMap should contain("s" -> ccWithLabelAndId.s)
-      vl.valueMap should contain("l" -> ccWithLabelAndId.l)
-      vl.valueMap should contain("o" -> ccWithLabelAndId.o.get)
-      vl.valueMap should contain("seq" -> ccWithLabelAndId.seq)
-      vl.valueMap should contain("map" -> ccWithLabelAndId.map)
-      vl.valueMap should contain("nested" -> ccWithLabelAndId.nested)
+      vl.valueMap should contain("s" -> cc.s)
+      vl.valueMap should contain("l" -> cc.l)
+      vl.valueMap should contain("o" -> cc.o.get)
+      vl.valueMap should contain("seq" -> cc.seq)
+      vl.valueMap should contain("map" -> cc.map)
+      vl.valueMap should contain("nested" -> cc.nested)
     }
 
     "have an Option @id annotation" in new Fixture {