@brief Get the vertices of the graph that share common properties.

`graph._commonProperties(vertex1Example, vertex2Examples, options)`

The function accepts an id, an example, a list of examples or even an empty
example as parameter for vertex1Example and vertex2Example.

The complexity of this method is **O(n)** with *n* being the maximal amount of vertices
defined by the parameters vertexExamples.

@PARAMS

@PARAM{vertex1Examples, object, optional}
Filter the set of source vertices, see [Definition of examples](#definition-of-examples)

@PARAM{vertex2Examples, object, optional}
Filter the set of vertices compared to, see [Definition of examples](#definition-of-examples)

@PARAM{options, object, optional}
An object defining further options. Can have the following values:
  * *vertex1CollectionRestriction* : One or a list of vertex-collection names that should be
      searched for source vertices.
  * *vertex2CollectionRestriction* : One or a list of vertex-collection names that should be
      searched for compare vertices.
  * *ignoreProperties* : One or a list of attribute names of a document that should be ignored.

@EXAMPLES

A route planner example, all locations with the same properties:

@EXAMPLE_ARANGOSH_OUTPUT{generalGraphModuleProperties1}
  var examples = require("@arangodb/graph-examples/example-graph.js");
  var graph = examples.loadGraph("routeplanner");
  graph._commonProperties({}, {});
~ examples.dropGraph("routeplanner");
@END_EXAMPLE_ARANGOSH_OUTPUT

A route planner example, all cities which share same properties except for population.

@EXAMPLE_ARANGOSH_OUTPUT{generalGraphModuleProperties2}
  var examples = require("@arangodb/graph-examples/example-graph.js");
  var graph = examples.loadGraph("routeplanner");
  graph._commonProperties({}, {}, {ignoreProperties: 'population'});
~ examples.dropGraph("routeplanner");
@END_EXAMPLE_ARANGOSH_OUTPUT