Expression constructor
      
      Expression({ 
    
    
- List<Expression> ? and,
- CostCategoryValues? costCategories,
- DimensionValues? dimensions,
- Expression? not,
- List<Expression> ? or,
- TagValues? tags,
Implementation
Expression({
  this.and,
  this.costCategories,
  this.dimensions,
  this.not,
  this.or,
  this.tags,
});