isEmpty(String) must not return false for whitespace-only values

This closes #214

Author: kwin

src/main/java/org/codehaus/plexus/util/StringUtils.java

@@ -156,9 +156,7 @@ public static String deleteWhitespace( String str )
     }
 
     /**
-     * <p>
      * Checks if a String is non <code>null</code> and is not empty (<code>length &gt; 0</code>).
-     * </p>
      *
      * @param str the String to check
      * @return true if the String is non-null, and not length zero
@@ -169,21 +167,18 @@ public static boolean isNotEmpty( String str )
     }
 
     /**
+     * Checks if a String is <code>null</code> or empty.
      * <p>
-     * Checks if a (trimmed) String is <code>null</code> or empty.
-     * </p>
-     * <p>
-     * <strong>Note:</strong> In future releases, this method will no longer trim the input string such that it works
-     * complementary to {@link #isNotEmpty(String)}. Code that wants to test for whitespace-only strings should be
-     * migrated to use {@link #isBlank(String)} instead.
-     * </p>
+     * <strong>Note:</strong> In releases prior 3.5.0, this method trimmed the input string such that it worked
+     * the same as {@link #isBlank(String)}. Since release 3.5.0 it no longer returns {@code true} for strings
+     * containing whitespace.
      *
      * @param str the String to check
-     * @return <code>true</code> if the String is <code>null</code>, or length zero once trimmed
+     * @return <code>true</code> if the String is <code>null</code>, or length zero
      */
     public static boolean isEmpty( String str )
     {
-        return ( ( str == null ) || ( str.trim().isEmpty() ) );
+        return ( ( str == null ) || ( str.isEmpty() ) );
     }
 
     /**

src/test/java/org/codehaus/plexus/util/StringUtilsTest.java

@@ -43,7 +43,7 @@ public void testIsEmpty()
     {
         assertEquals( true, StringUtils.isEmpty( null ) );
         assertEquals( true, StringUtils.isEmpty( "" ) );
-        assertEquals( true, StringUtils.isEmpty( " " ) );
+        assertEquals( false, StringUtils.isEmpty( " " ) );
         assertEquals( false, StringUtils.isEmpty( "foo" ) );
         assertEquals( false, StringUtils.isEmpty( "  foo  " ) );
     }
@@ -61,6 +61,16 @@ public void testIsNotEmpty()
         assertEquals( true, StringUtils.isNotEmpty( "  foo  " ) );
     }
 
+    @Test
+    public void testIsNotEmptyNegatesIsEmpty()
+    {
+        assertEquals( !StringUtils.isEmpty( null ), StringUtils.isNotEmpty( null ) );
+        assertEquals( !StringUtils.isEmpty( "" ), StringUtils.isNotEmpty( "" ) );
+        assertEquals( !StringUtils.isEmpty( " " ), StringUtils.isNotEmpty( " " ) );
+        assertEquals( !StringUtils.isEmpty( "foo" ), StringUtils.isNotEmpty( "foo" ) );
+        assertEquals( !StringUtils.isEmpty( "  foo  " ), StringUtils.isNotEmpty( "  foo  " ) );
+    }
+
     /**
      * <p>testIsBlank.</p>
      */