TextTokenizerMixin constructor Null safety

1. text_analysis
2. implementation
3. TextTokenizerMixin
4. TextTokenizerMixin constructor

TextTokenizerMixin class

1. Constructors
2. TextTokenizerMixin
3. Properties
4. analyzer
5. hashCode
6. runtimeType
7. tokenFilter
8. Methods
9. noSuchMethod
10. tokenize
11. tokenizeJson
12. toString
13. Operators
14. operator ==