Location attributes are not correctly updated

ui/org.eclipse.pde.core/src/org/eclipse/pde/internal/core/target/TargetDefinition.java

@@ -1269,6 +1269,7 @@ private void updateIUContainerElements(Element containersElement, List<Element>
 					} else {
 						oldContainersByRepo.get(repoURL).remove(0);
 					}
+					TargetDefinitionDocumentTools.updateAttributes(oldContainer, container);
 				} else {
 					Node movedContainer = fDocument.importNode(container, true);
 					TargetDefinitionDocumentTools.addChildWithIndent(containersElement, movedContainer);

ui/org.eclipse.pde.core/src/org/eclipse/pde/internal/core/target/TargetDefinitionDocumentTools.java

@@ -16,7 +16,10 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Comparator;
+import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 
 import org.eclipse.core.runtime.preferences.IEclipsePreferences;
 import org.eclipse.core.runtime.preferences.InstanceScope;
@@ -85,6 +88,33 @@ public static void addChildWithIndent(Node parent, Node child) {
 		appendTextNode(parent, false);
 	}
 
+	public static void updateAttributes(Element oldElement, Element newElement) {
+		Map<String, String> previous = asMap(oldElement.getAttributes());
+		Map<String, String> current = asMap(newElement.getAttributes());
+		HashSet<String> all = new HashSet<>();
+		all.addAll(previous.keySet());
+		all.addAll(current.keySet());
+		for (String attr : all) {
+			if (current.containsKey(attr)) {
+				// if the current element contains the attribute then set it to
+				// the current value
+				oldElement.setAttribute(attr, current.get(attr));
+			} else {
+				// otherwise remove the attribute
+				oldElement.removeAttribute(attr);
+			}
+		}
+	}
+
+	private static Map<String,String> asMap(NamedNodeMap attributes) {
+		HashMap<String, String> map = new HashMap<>();
+		for (int i = 0; i < attributes.getLength(); i++) {
+			Node item = attributes.item(i);
+			map.put(item.getNodeName(), item.getNodeValue());
+		}
+		return map;
+	}
+
 	/**
 	 * For all the children of the parentElement, if any of the oldElements are not
 	 * found in the newElements list then they are removed. All newElements that are

ui/org.eclipse.pde.ui.tests/src/org/eclipse/pde/ui/tests/target/IUBundleContainerTests.java

@@ -15,6 +15,7 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 
@@ -633,6 +634,44 @@ public void testSerialization3() throws Exception {
 		deserializationTest(location);
 	}
 
+	@Test
+	public void testSerializationOnlyLocationAttributeChanged() throws Exception {
+		URI uri = getURI("/tests/sites/site.a.b");
+		String[] unitIds = new String[] { "feature.b.feature.group" };
+		IInstallableUnit[] units = getUnits(unitIds, uri);
+
+		IUBundleContainer location1 = createContainer(units, new URI[] { uri },
+				IUBundleContainer.INCLUDE_ALL_ENVIRONMENTS | IUBundleContainer.INCLUDE_SOURCE);
+		String xml1 = location1.serialize();
+		assertIncludeAllPlatform(xml1, true);
+		assertIncludeMode(xml1, "slicer");
+		assertIncludeSource(xml1, true);
+
+		IUBundleContainer location2 = createContainer(units, new URI[] { uri },
+				IUBundleContainer.INCLUDE_ALL_ENVIRONMENTS); // no source
+		String xml2 = location2.serialize();
+		assertIncludeAllPlatform(xml2, true);
+		assertIncludeMode(xml2, "slicer");
+		assertIncludeSource(xml2, false); // no source
+
+		ITargetDefinition td = getTargetService().newTarget();
+		td.setTargetLocations(new ITargetLocation[] { location1 });
+		ByteArrayOutputStream out1 = new ByteArrayOutputStream();
+		TargetDefinitionPersistenceHelper.persistXML(td, out1);
+		String resultXmlOld = new String(out1.toByteArray());
+
+		td.setTargetLocations(new ITargetLocation[] { location2 });
+		ByteArrayOutputStream out2 = new ByteArrayOutputStream();
+		TargetDefinitionPersistenceHelper.persistXML(td, out2);
+		String resultXmlNew = new String(out2.toByteArray());
+
+		String normalizedOld = resultXmlOld.replaceAll("\r?\n[ \t]*", "");
+		String normalizedNew = resultXmlNew.replaceAll("\r?\n[ \t]*", "");
+
+		assertNotEquals(normalizedOld, normalizedNew);
+		assertEquals(normalizedOld, normalizedNew.replace("includeSource=\"false\"", "includeSource=\"true\""));
+	}
+
 	@Test
 	public void testSerializationVersionRange() throws Exception {
 		URI uri = getURI("/tests/sites/site.a.b");