Java BigDecimal data converting to opposite sign long
<p>According to the Java 7 <a href="https://docs.oracle.com/javase/7/docs/api/java/math/BigDecimal.html#longValue()" rel="nofollow">documentation</a>, the method <strong>longValue</strong> from class <strong>java.math.BigDecimal</strong> can return a result with the opposite sign.</p>

<blockquote>
  <p>Converts this BigDecimal to a long. This conversion is analogous to the narrowing primitive conversion from double to short as defined in section 5.1.3 of The Java™ Language Specification: any fractional part of this BigDecimal will be discarded, and if the resulting "BigInteger" is too big to fit in a long, only the low-order 64 bits are returned. Note that this conversion can lose information about the overall magnitude and precision of this BigDecimal value as well as <strong>return a result with the opposite sign</strong>.</p>
</blockquote>

<p>In what case is it possible?</p>