Bug 351231 - [prefs] EclipsePreferences#flush method should
be synchronized
diff --git a/bundles/org.eclipse.equinox.preferences/src/org/eclipse/core/internal/preferences/EclipsePreferences.java b/bundles/org.eclipse.equinox.preferences/src/org/eclipse/core/internal/preferences/EclipsePreferences.java
index 816bd10..c2699a7 100644
--- a/bundles/org.eclipse.equinox.preferences/src/org/eclipse/core/internal/preferences/EclipsePreferences.java
+++ b/bundles/org.eclipse.equinox.preferences/src/org/eclipse/core/internal/preferences/EclipsePreferences.java
@@ -322,7 +322,7 @@
 	/*
 	 * @see org.osgi.service.prefs.Preferences#flush()
 	 */
-	public void flush() throws BackingStoreException {
+	synchronized public void flush() throws BackingStoreException {
 		// illegal state if this node has been removed
 		checkRemoved();