(optional) If a default element is dropped, it can be passed here to help generation. Structure:
unknown [type: Array, elementType: String] - The unslotted elements to be used for generated.
measures [type: Array, elementType: String] - The measures (unique name) to be used for generation.
rows [type: Array, elementType: String] - The rows (unique name) to be used for generation.
columns [type: Array, elementType: String] - The columns (unique name) to be used for generation.
slicers [type: Array, elementType: String] - The slicers (unique name) to be used for generation.