The type grails.testing.gorm.DomainUnitTest$Trait$FieldHelper$1 cannot be resolved. It is indirectly referenced from required .class files

[kszymko]

Eclipse 4.7.2
Gradle 4.6 (testCompile 'org.grails:grails-gorm-testing-support:1.1.4')

import grails.testing.gorm.DomainUnitTest
import spock.lang.Specification
import spock.lang.Unroll

class DomainSpec extends Specification implements DomainUnitTest<Domain> {

In-eclipse > Project > Clean (start a build immediately) gives error:
The type grails.testing.gorm.DomainUnitTest$Trait$FieldHelper$1 cannot be resolved. It is indirectly referenced from required .class files

I have checked internals of referenced grails-gorm-testing-support-1.1.4.jar

• it does not contain grails.testing.gorm.DomainUnitTest$Trait$FieldHelper$1.class

Is it an IDE related issue? If so, any tips on how to get rid of it?