[java] mention performance in inspection description (IJ-CR-129155)

GitOrigin-RevId: afd288ea265904dd5446fc24c092cb650d986abd

java/java-impl/src/inspectionDescriptions/UnnecessaryToStringCall.html

@@ -7,7 +7,9 @@ Reports calls to <code>toString()</code> that are used in the following cases:
   <li>In the methods of <code>java.io.PrintWriter</code> or <code>java.io.PrintStream</code></li>
   <li>in the methods <code>org.slf4j.Logger</code></li>
 </ul>
-<p>In these cases, conversion to string will be handled by the underlying library methods, and the explicit call to <code>toString()</code> is not needed.</p>
+<p>In these cases, conversion to string will be handled by the underlying library methods,
+  and the explicit call to <code>toString()</code> is not needed.
+  Removing redundant <code>toString()</code> calls can occasionally even improve performance and reduce object allocations</p>
 <p>Example:</p>
 <pre><code>
   System.out.println(this.toString())
@@ -21,6 +23,8 @@ Reports calls to <code>toString()</code> that are used in the following cases:
   Note that without the <code>toString()</code> call, the code semantics might be different: if the expression is null,
   then the <code>null</code> string will be used instead of throwing a <code>NullPointerException</code>.</p>
   <p>Use the <b>Report only when qualifier is known to be not-null</b> option to avoid warnings for the values that could potentially be null.
+  Removing the explicit <code>toString()</code> in these cases will change the runtime semantics
+  from throwing a <code>NullPointException</code> to silently accepting the value when it is <code>null</code>.
 </p>
 </body>
 </html>