This document lists all the validators supported and gives users are guideline on how to use them.
The if, then and else keywords allow the application of a subschema based on the outcome of another schema, much like the if/then/else constructs you’ve probably seen in traditional programming languages.
If if is valid, then must also be valid (and else is ignored.) If if is invalid, else must also be valid (and then is ignored).
For usage, please refer to the test cases at https://github.com/networknt/json-schema-validator/blob/master/src/test/resources/tests/if.json