static <V> ExpressionBiVisitor<V, Void> toBiVisitor(ExpressionVisitor<V> visitor) {
    return new ExpressionBiVisitor<V, Void>() {
      @Override
      public V visit(Call call, @Nullable Void context) {
        return visitor.visit(call);
      }

      @Override
      public V visit(Constant constant, @Nullable Void context) {
        return visitor.visit(constant);
      }

      @Override
      public V visit(Path path, @Nullable Void context) {
        return visitor.visit(path);
      }

    };
  }
Converts a {@link ExpressionVisitor} into a {@link ExpressionBiVisitor} (with ignored payload).
criteria/common/src/org/immutables/criteria/expression/Expressions.java