public boolean isNeverNullable() {
        return !nullableSelf && !nullableOther;
    }
Returns if this JoinType always produce results that are <em>NEVER</em>
{@code null} for entities belonging to another Stage.

@return if this JoinType always produce results that are <em>NEVER</em>
{@code null} for entities belonging to another Stage.
runtime-parent/runtime-join/src/main/java/com/speedment/runtime/join/stage/JoinType.java