re-enabled openapi4j parser validation.

Author: hauner

build.gradle

@@ -60,7 +60,7 @@ dependencies {
     implementation 'org.codehaus.groovy:groovy:2.5.4'
     implementation 'org.jetbrains.kotlin:kotlin-stdlib'
     implementation 'io.swagger.parser.v3:swagger-parser:2.0.17'
-    implementation 'org.openapi4j:openapi-parser:0.8-SNAPSHOT'
+    implementation 'org.openapi4j:openapi-parser:0.8'
     implementation 'com.google.googlejavaformat:google-java-format:1.7'
     compileOnly "com.github.hauner.openapi:openapi-processor-api:$processorApiVersion"