Titan 1.0.0 FIXED configuration "set-vertex-id" - can be overriden? - configuration

Question

I'm trying to override the graph.set-vertex-id configuration in Titan 1.0.0
By loading the configuration from an xml file:
cache.db-cache-time = 180000
cache.db-cache-size = 0.25
graph.set-vertex-id=true
storage.batch-loading=true
....
I'm getting the error :
Local setting graph.set-vertex-id=true (Type: FIXED) is overridden by globally managed value (false). Use the ManagementSystem interface instead of the local configuration to control this setting.
I also tried
BaseConfiguration configuration = new BaseConfiguration();
configuration.setProperty("storage.hostname", "any_hostname");
configuration.setProperty("storage.backend", "thrift");
configuration.setProperty("graph.set-vertex-id", Boolean.TRUE);
titanGraph = TitanFactory.open(configuration);
But by checking the config with TitanManagement
titanGraph.openManagement().get("graph.set-vertex-id");
I can see that it's still 'false'.
Has anyone tried to assign custom vertices ids in this version of Titan? Before the upgrade we used Titan 0.4.2 and it worked just fine.
The documentation (http://s3.thinkaurelius.com/docs/titan/1.0.0/configuration.html ) says that
GLOBAL: These options are always read from the cluster configuration and cannot be overwritten on an instance basis.
FIXED: Like GLOBAL, but the value cannot be changed once the Titan cluster is initialized.
When the first Titan instance in a cluster is started, the global configuration options are initialized from the provided local configuration file. Subsequently changing global configuration options is done through Titan’s management API.
To access the management API, call g.getManagementSystem() on an open Titan instance handle g. For example, to change the default caching behavior on a Titan cluster:
mgmt = graph.openManagement()
mgmt.get('cache.db-cache')
// Prints the current config setting
mgmt.set('cache.db-cache', true)
// Changes option
mgmt.get('cache.db-cache')
// Prints 'true'
mgmt.commit()
// Changes take effect
Firstly, there is no getManagementSystem() on a graph in Titan 1.0.0. Secondly, overriding the "graph.set-vertex-id" config like that will throw another error, because at this point the graph is already initialised:
Cannot change the fixed configuration option: root.graph.set-vertex-id
Thank you !