Add description for the simpleNameFromSerialName function

Author: rlazo

firebase-vertexai/src/test/java/com/google/firebase/vertexai/common/util/descriptorToJson.kt

@@ -138,6 +138,22 @@ internal fun typeNameFromKind(kind: SerialKind): String {
   }
 }
 
+/**
+ * Extracts the name expected for a class from its serial name.
+ *
+ * Our serialization classes are nested within the public-facing classes, and that's the name we
+ * want in the json output. There are two class names
+ *
+ * - `com.google.firebase.vertexai.type.Content.Internal` for regular scenarios
+ * - `com.google.firebase.vertexai.type.Content.Internal.SomeClass` for nested classes in the
+ * serializer.
+ *
+ * For the later time we need the second to last component, for the former we need the last
+ * component.
+ *
+ * Additionally, given that types can be nullable, we need to strip the `?` from the end of the
+ * name.
+ */
 internal fun simpleNameFromSerialName(serialName: String): String =
   serialName
     .split(".")