These are the four errors in the engine module:

/engine/src/main/java/org/hibernate/validator/internal/util/CollectionHelper.java:[61,44] incompatible types: java.util.HashSet<capture#1 of ? extends T> cannot be converted to java.util.HashSet<T>

/engine/src/main/java/org/hibernate/validator/internal/metadata/aggregated/ReturnValueMetaData.java:[62,64] incompatible types: java.util.List<capture#2 of ? extends org.hibernate.validator.internal.metadata.facets.Cascadable> cannot be converted to java.util.List<org.hibernate.validator.internal.metadata.facets.Cascadable>

/engine/src/main/java/org/hibernate/validator/internal/metadata/aggregated/ValidatableParametersMetaData.java:[25,46] incompatible types: java.util.HashSet<capture#3 of ? extends org.hibernate.validator.internal.metadata.facets.Cascadable> cannot be converted to java.lang.Iterable<org.hibernate.validator.internal.metadata.facets.Cascadable>

/engine/src/main/java/org/hibernate/validator/internal/metadata/raw/BeanConfiguration.java:[57,54] incompatible types: java.util.HashSet<capture#4 of ? extends org.hibernate.validator.internal.metadata.raw.ConstrainedElement> cannot be converted to java.util.Set<org.hibernate.validator.internal.metadata.raw.ConstrainedElement>