PredicateExpression constructor Null safety

1. conduit_core
2. conduit
3. PredicateExpression
4. PredicateExpression constructor

PredicateExpression class

1. Constructors
2. PredicateExpression
3. Properties
4. hashCode
5. inverse
6. runtimeType
7. Methods
8. noSuchMethod
9. toString
10. Operators
11. operator ==