swagger: Document meaning of value -1 for parentId of TreeDataModel

Fixes eclipse-cdt-cloud/trace-server-protocol#65

Signed-off-by: Bernd Hufmann <[email protected]>

Author: bhufmann

trace-server/org.eclipse.tracecompass.incubator.trace.server.jersey.rest.core/src/org/eclipse/tracecompass/incubator/internal/trace/server/jersey/rest/core/model/TreeDataModel.java

@@ -28,14 +28,13 @@ public interface TreeDataModel {
     /**
      * @return The ID.
      */
-    @Schema(description = "Unique id to identify this entry in the backend", required = true)
+    @Schema(description = "Unique ID to identify this entry in the backend", required = true)
     long getId();
 
     /**
      * @return The parent ID.
      */
-    @Schema(description = "Unique id to identify this parent's entry, " +
-            "optional if this entry does not have a parent.")
+    @Schema(description = "Optional unique ID to identify this entry's parent. If the parent ID is -1 or omitted, this entry has no parent.")
     long getParentId();
 
     /**