ConfigurationManagementGraph to throw Exception with custom ID setting

[li-boxuan]

janusgraph/janusgraph-core/src/main/java/org/janusgraph/graphdb/management/ConfigurationManagementGraph.java

Lines 122 to 131 in 3b8843f

	public void createConfiguration(final Configuration config) {
	Preconditions.checkArgument(config.containsKey(PROPERTY_GRAPH_NAME),
	String.format("Please include the property \"%s\" in your configuration.",
	PROPERTY_GRAPH_NAME
	));
	final Map<Object, Object> map = ConfigurationConverter.getMap(config);
	final Vertex v = graph.addVertex(T.label, VERTEX_LABEL);
	map.forEach((key, value) -> v.property((String) key, value));
	v.property(PROPERTY_TEMPLATE, false);
	graph.tx().commit();

uses ConfigurationManagementGraph, a special meta-graph to store real graph configs as vertex properties. By design, this "meta-graph" doesn't support custom vertex ID, because obviously users don't have a way to specify vertex IDs.

This PR adds a check in ConfigurationManagementGraph to make it clear that it's by design.

Fixes #4535

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