setUnitMappings(mUnitMappings) {
			_set("unitMappings", mUnitMappings);
		}
Sets custom unit mappings.
Unit mappings contain key value pairs (both strings)
* {string} key: a new entry which maps to an existing unit key
* {string} value: an existing unit key

Example:
<code>
{
 "my": "my-custom-unit",
 "cm": "length-centimeter"
}
</code>
Note: It is possible to create multiple entries per unit key.
Call with <code>null</code> to delete unit mappings.
@param {object} mUnitMappings unit mappings
@private
@since 1.116.0