The spec for OptionalDouble.hashCode() says:

     * Returns the hash code value of the present value, if any, or 0 (zero) if
     * no value is present.

However it doesn't happen with JDK8b82-lambda:

--------------------------------------------------
import java.util.OptionalDouble;
import java.util.OptionalInt;
import java.util.OptionalLong;

public class EmptyOptionalDoubleHashCode {

    public static void main(String[] args) {
        System.out.println("OptionalInt.empty().hashCode() = " + OptionalInt.empty().hashCode());
        System.out.println("OptionalLong.empty().hashCode() = " + OptionalLong.empty().hashCode());
        System.out.println("OptionalDouble.empty().hashCode() = " + OptionalDouble.empty().hashCode());
    }
}
--------------------------------------------------

The output is:

OptionalInt.empty().hashCode() = 0
OptionalLong.empty().hashCode() = 0
OptionalDouble.empty().hashCode() = 2146959360

The following JCK test fails due to this issue:
api/java_util/OptionalDouble/index.html#General[hashCodeEmptyZeroValue]