public ObjectTypeAssert isCollectionOf(Class componentType) {
    isNotNull();
    isExactlyInstanceOf(CollectionTypeImpl.class);
    org.assertj.core.api.Assertions.assertThat(((CollectionTypeImpl) actual).getElementType())
        .isExactlyInstanceOf(componentType);

    return this;
  }
Custom Assertion to validate {@link ObjectType} instances.
geode-core/src/test/java/org/apache/geode/cache/query/internal/types/ObjectTypeAssert.java