{ "openapi": "3.0.0", "info": { "title": "Employee API", "version": "1.0.0" }, "paths": { "/employees": { "get": { "summary": "Get list of employees", "responses": { "200": { "description": "A list of employees", "content": { "application/json": { "s...

This is because your json schema is missing some elements, try this one;