In the following document, a wrong package name is used.
By modifying to "io.swagger.annotations.*" from "io.openapi.annotations.*", mvn clean install works as expected.

https://access.redhat.com/documentation/en-us/red_hat_fuse/7.7/html/apache_cxf_development_guide/openapiextended

CHAPTER 54. EXTENDING JAX-RS ENDPOINTS WITH OPENAPI SUPPORT

54.2.2. Enabling OpenAPI

import io.openapi.annotations.*

Example 55.5 Example Resource class

import io.openapi.annotations.Api;
import io.openapi.annotations.ApiOperation;
import io.openapi.annotations.ApiParam;
import io.openapi.annotations.ApiResponse;
import io.openapi.annotations.ApiResponses;