@Override
        protected FieldValue convertMap(MapFieldValue<FieldValue, FieldValue> map) {
            var values = new Array<>(new ArrayDataType(expression.getOutputType()), map.size());
            for (var entry : map.entrySet())
                values.add(doConvert(new MapEntryFieldValue(entry.getKey(), entry.getValue())));
            return values;
        }
Converts a map into an array by passing each entry through the expression.
indexinglanguage/src/main/java/com/yahoo/vespa/indexinglanguage/expressions/ForEachExpression.java