import java.math.BigInteger;

public class Foo {
    private BigInteger field = new BigInteger("10");
    private BigInteger field2 = new BigInteger("20");
    
    public boolean check(final BigInteger param) {
        final BigInteger other = new BigInteger("20");

        return (field == null
                || param != field   // warning expected: Use equals() to compare object references. 
                && other != field)  // warning expected: Use equals() to compare object references. 
            && param.testBit(field2.intValue())
            && other.testBit(field2.intValue());
    }
}