In this case, all of the specified input attributes are made available to the enclosing definition. If an attribute of the same name has already been provided, then the values are combined with it.
Multi-value definitions are <AttributeDefinition> or <DataConnector> types which consume multiple attribute values at once. These values are often, but not always, from one input. Nearly all AttributeDefinition types are multi-value capable. In this case all the attributes and values are made available and values from multiple like-named attributes are combined.
In this situation it is common to only specify a single attribute via attributeNames, but this is by no means required and so this mechanism can be used to combine the values from multiple attributes from the same DataConnector into one output attribute.
The ComputedId and StoredId DataConnectors in contrast require a single value (which may come from multiple sources, all but one of which would need to be empty).
This is the identifier of a DataConnector plugin to include as a dependency
These are the attributes to pull from the connector's results as dependencies (a single name can of course be specified).
Mutually exclusive with allAttributes
If present and "true", indicates that all the connector's attributes should be supplied as dependencies.
Mutually exclusive with attributeNames
The following attribute definition combines the attribute values from four attributes from three input sources. After this runs the output attribute "MultiIn" will contain:
All the values from the attribute definition 'attribute1'
All the values from the attributes 'attribute2' and 'attribute3' sourced from the data connector 'connector1'
All the values from the attributes 'attribute4' sourced from the data connector 'connector2'
This is because Simple attribute definitions are multi-value definitions