[JENKINS-13599] Provided better implementation of

DoxygenDirectoryParser#isDirectoryAbsolute(). The previous implementation would
incorrectly think that doc was absolute because java.io.File found /home/y/doc

src/main/java/hudson/plugins/doxygen/DoxygenDirectoryParser.java

@@ -49,7 +49,6 @@ public DoxygenDirectoryParser(String publishType, String doxyfilePath, String do
     }
 
     public FilePath invoke(java.io.File workspace, VirtualChannel channel) throws IOException {
-
         try {
             return (DoxygenArchiverDescriptor.DOXYGEN_HTMLDIRECTORY_PUBLISHTYPE).equals(publishType)
                     ? retrieveDoxygenDirectoryFromHudsonConfiguration(doxygenHtmlDirectory, new FilePath(workspace))
@@ -164,26 +163,34 @@ public Boolean invoke(File f, VirtualChannel channel) throws IOException, Interr
         return result;
     }
 
-	protected Boolean isDirectoryAbsolute(FilePath base,
-			final String finalComputedDoxygenDir) throws IOException,
-			InterruptedException {
-		Boolean absolute = false;
-		absolute = base.act(new FilePath.FileCallable<Boolean>() {
-			public Boolean invoke(File f, VirtualChannel channel)
-					throws IOException, InterruptedException {
-
-				File parentFile = new File(finalComputedDoxygenDir).getParentFile();
-				if (parentFile == null) {
-					// A computed directory with no parent will return null.
-					// Guard against a NullPointerException
-					return false;
-				}
-
-				return parentFile.exists();
-			}
-		});
-		return absolute;
-	}
+    // See https://issues.jenkins-ci.org/browse/JENKINS-13599
+    protected boolean isDirectoryAbsolute(String path) {
+        File file = new File(path);
+        String absolutePath = file.getAbsolutePath();
+        LOGGER.info(String.format("passed in path:%s, absolutePath:%s", 
+                path, absolutePath));
+        if(path.equals(file.getAbsolutePath())) {
+            return true;
+        }
+        else {
+            return false;
+        }    
+    }
+
+    protected Boolean isDirectoryAbsolute(FilePath base,
+                                          final String finalComputedDoxygenDir) throws IOException,
+        InterruptedException {
+        Boolean absolute = false;
+        absolute = base.act(new FilePath.FileCallable<Boolean>() {
+                public Boolean invoke(File f, VirtualChannel channel)
+                throws IOException, InterruptedException {
+
+                    // See https://issues.jenkins-ci.org/browse/JENKINS-13599
+                    return isDirectoryAbsolute(finalComputedDoxygenDir);
+                }
+            });
+        return absolute;
+    }
 
     /**
      * Load the Doxyfile Doxygen file in memory