public static FieldPathEntry newAllKeysLookupEntry(DataType resultingDataType) {
        return new FieldPathEntry(true, false, resultingDataType);
    }
Creates a new field path entry that digs through all the keys of a map or weighted set.

@param resultingDataType The datatype of the keys in the map or weighted set.
@return The new field path entry.
document/src/main/java/com/yahoo/document/FieldPathEntry.java