Don't write empty probe arrays
This optimizations reduces the size of exec files significantly in
setups where execution data is dumped after every test case.
diff --git a/org.jacoco.doc/docroot/doc/changes.html b/org.jacoco.doc/docroot/doc/changes.html
index 5bf8f95..ef82fde 100644
--- a/org.jacoco.doc/docroot/doc/changes.html
+++ b/org.jacoco.doc/docroot/doc/changes.html
@@ -22,6 +22,9 @@
<h3>Non-functional Changes</h3>
<ul>
+ <li>Empty probe arrays are not written to execution data files any more. This
+ reduces exec file size significantly for per-test data dumps.
+ (GitHub <a href="https://github.com/jacoco/jacoco/issues/387">#387</a>).</li>
<li>Require at least Maven 3.0 for build of JaCoCo.</li>
</ul>