### Eclipse Workspace Patch 1.0
#P org.eclipse.jdt.core
Index: model/org/eclipse/jdt/internal/core/ProjectReferenceChange.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/ProjectReferenceChange.java,v
retrieving revision 1.4
diff -u -r1.4 ProjectReferenceChange.java
--- model/org/eclipse/jdt/internal/core/ProjectReferenceChange.java	14 Jan 2008 09:55:21 -0000	1.4
+++ model/org/eclipse/jdt/internal/core/ProjectReferenceChange.java	28 Jan 2008 16:51:58 -0000
@@ -15,6 +15,7 @@
 
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.IProjectDescription;
+import org.eclipse.core.resources.IResource;
 import org.eclipse.core.resources.IWorkspace;
 import org.eclipse.core.resources.IWorkspaceRoot;
 import org.eclipse.core.resources.IWorkspaceRunnable;
@@ -95,7 +96,7 @@
 					requiredProjectArray[i] = wksRoot.getProject(requiredProjectNames[i]);
 				}
 				description.setDynamicReferences(requiredProjectArray);
-				projectResource.setDescription(description, null);
+				projectResource.setDescription(description, IResource.AVOID_NATURE_CONFIG, null);
 			}
 		};
 		try {
#P org.eclipse.jdt.core.tests.model
Index: src/org/eclipse/jdt/core/tests/model/ClasspathTests.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/model/ClasspathTests.java,v
retrieving revision 1.166
diff -u -r1.166 ClasspathTests.java
--- src/org/eclipse/jdt/core/tests/model/ClasspathTests.java	9 Jan 2008 17:45:34 -0000	1.166
+++ src/org/eclipse/jdt/core/tests/model/ClasspathTests.java	28 Jan 2008 16:52:00 -0000
@@ -3843,6 +3843,26 @@
 }
 
 /*
+ * Ensures that updating the project references doesn't throw a runtime excetion
+ * (regression test for https://bugs.eclipse.org/bugs/show_bug.cgi?id=216747 )
+ */
+public void testUpdateProjectReferences() throws CoreException {
+	try {
+		createJavaProject("P1");
+		IJavaProject p = createJavaProject("P2");
+		p.setRawClasspath(new IClasspathEntry[] {JavaCore.newProjectEntry(new Path("/P1"))}, null);
+		IProject[] references = p.getProject().getDescription().getDynamicReferences();
+		assertResourcesEqual(
+			"Unexpected resources", 
+			"/P1", 
+			references);
+	} finally {
+		deleteProject("P1");
+		deleteProject("P2");
+	}
+}
+
+/*
  * Ensures that unknown classpath attributes in a .classpath file are not lost when read and rewritten.
  * (regression test for bug 101425 Classpath persistence should be resilient with unknown attributes)
  */