Using the latest version of the library in gcloud-java repository leads to an exception

[yevhenii-nadtochii]

Using of the latest version of spine-mc-java in gcloud-java repository fails the build with an exception.

The problematic versions are 2.0.0-SNAPSHOT.90 / 2.0.0-SNAPSHOT.91.

Exception in thread "main" java.lang.IllegalStateException: Unknown type: `type.googleapis.com/google.pubsub.v1.PubsubMessage`.
        at io.spine.validation.java.TypeSystem.unknownType(TypeSystem.kt:220)
        at io.spine.validation.java.TypeSystem.classNameFor(TypeSystem.kt:110)
        at io.spine.validation.java.TypeSystem.messageValueToJava(TypeSystem.kt:157)
        at io.spine.validation.java.TypeSystem.valueToJava(TypeSystem.kt:130)
        at io.spine.validation.java.SimpleRuleGenerator.<init>(SimpleRuleGenerator.kt:82)
        at io.spine.validation.java.SimpleRuleGeneratorKt.generatorForSingular(SimpleRuleGenerator.kt:153)
        at io.spine.validation.java.SimpleRuleGeneratorKt.generatorForSimple(SimpleRuleGenerator.kt:146)
        at io.spine.validation.java.JavaCodeGeneration.generatorFor(CodeGenerator.kt:115)
        at io.spine.validation.java.JavaValidationRenderer.generateValidationCode(JavaValidationRenderer.java:221)
        at io.spine.validation.java.JavaValidationRenderer.generateCode(JavaValidationRenderer.java:141)
        at io.spine.validation.java.JavaValidationRenderer.lambda$render$3(JavaValidationRenderer.java:128)
        at ...

> Task :pubsub:launchProtoDataMain FAILED