The map of a symbology attribute and its override used to fetch a symbol from the dictionary symbol style. A DictionarySymbolStyle uses a collection of expected attribute names to build a symbol based on input values. When initialized, fields in the input dataset are mapped to the expected attribute names using case-insensitive matching. If your data uses a different name for an expected symbol attribute, use the DictionaryRenderer.symbologyFieldOverrides to map an expected field to the correct field in your data. You can also exclude an expected field by providing an empty string for it in the overrides.