diff --git a/platform/util/src/com/intellij/openapi/util/text/StringUtil.java b/platform/util/src/com/intellij/openapi/util/text/StringUtil.java
index bc4181e3cf9c..b50ab3e3cbc9 100644
--- a/platform/util/src/com/intellij/openapi/util/text/StringUtil.java
+++ b/platform/util/src/com/intellij/openapi/util/text/StringUtil.java
@@ -281,6 +281,18 @@ public class StringUtil extends StringUtilRt {
     return getPackageName(fqName, '.');
   }
 
+  /**
+   * Given a fqName returns the package name for the type or the containing type.
+   * <p/>
+   * <ul>
+   * <li><code>java.lang.String</code> -> <code>java.lang</code></li>
+   * <li><code>java.util.Map.Entry</code> -> <code>java.util.Map</code></li>
+   * </ul>
+   *
+   * @param fqName    a fully qualified type name. Not supposed to contain any type arguments
+   * @param separator the separator to use. Typically '.'
+   * @return the package name of the type or the declarator of the type. The empty string if the given fqName is unqualified
+   */
   @NotNull
   @Contract(pure = true)
   public static String getPackageName(@NotNull String fqName, char separator) {
diff --git a/platform/util/testSrc/com/intellij/util/text/StringUtilTest.java b/platform/util/testSrc/com/intellij/util/text/StringUtilTest.java
index 59ee8a8280e7..2d80c681bb87 100644
--- a/platform/util/testSrc/com/intellij/util/text/StringUtilTest.java
+++ b/platform/util/testSrc/com/intellij/util/text/StringUtilTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2015 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -380,4 +380,11 @@ public class StringUtilTest extends TestCase {
     assertEquals("<![CDATA[abcd]]]><![CDATA[]>efgh]]>", XmlStringUtil.wrapInCDATA("abcd]]>efgh"));
     assertEquals("<![CDATA[123<![CDATA[wow<&>]]]><![CDATA[]>]]]><![CDATA[]><![CDATA[123]]>", XmlStringUtil.wrapInCDATA("123<![CDATA[wow<&>]]>]]><![CDATA[123"));
   }
+
+  public void testGetPackageName() {
+    assertEquals("java.lang", StringUtil.getPackageName("java.lang.String"));
+    assertEquals("java.util.Map", StringUtil.getPackageName("java.util.Map.Entry"));
+    assertEquals("Map", StringUtil.getPackageName("Map.Entry"));
+    assertEquals("", StringUtil.getPackageName("Number"));
+  }
 }