Merging OpenAPI Schemas in Micronaut

Merging your own schemas into the generated OpenAPI specification is pretty straightforward. With OpenAPI integrated into your application, all you need to do is to add the system property micronaut.openapi.additional.files

build.gradle

tasks.withType(GroovyCompile) {
   ...
   groovyOptions.forkOptions.jvmArgs.add("-Dmicronaut.openapi.additional.files=${project.projectDir}/src/main/resources/swagger".toString())
   ...
}

Specifying the location of the additional schema files. In this case I have it set to src/main/resources/swagger.

It is worth noting what information is taken from additional files:

Optional.ofNullable(from.getTags()).ifPresent(tags -> tags.forEach(to::addTagsItem));
Optional.ofNullable(from.getServers()).ifPresent(servers -> servers.forEach(to::addServersItem));
Optional.ofNullable(from.getSecurity()).ifPresent(securityRequirements -> securityRequirements.forEach(to::addSecurityItem));
Optional.ofNullable(from.getPaths()).ifPresent(paths -> paths.forEach(to::path));
Optional.ofNullable(from.getComponents()).ifPresent(components -> { ... });

The snippet of code above from the OpenApiApplicationVisitor.java class in the micronaut-open-api project shows that you can integrate tag, server, security, path and component info from other schemas.

You can find a working example using micronaut 1.3.5 that integrates a security schema on github.