code: func (c *expressionCompiler) getFieldName(fieldName string) (mappedFieldName string, isJSONField bool) {
  	// If this field name references a joinable table, we will not say that it
  	// is a JSON field even though it might contain a dot.
  	for _, j := range c.joins {
  		if j.HandlesFieldName(fieldName) {
  			return fieldName, false
  		}
  	}
  
  	mappedFieldName, isColumnField := fieldMap[fieldName]
  	if isColumnField {
  		return Column(WorkItemStorage{}.TableName(), mappedFieldName), false
  	}
  
  	if strings.Contains(fieldName, ".") || strings.Contains(fieldName, "_") {
  		// leave field untouched
  		return fieldName, true
  	}
  	return Column(WorkItemStorage{}.TableName(), fieldName), false
  }
docs: // getFieldName applies any potentially necessary mapping to field names (e.g.
  // SpaceID -> space_id) and tells if the field is stored inside the jsonb column
  // (last result is true then) or as a normal column.