### Eclipse Workspace Patch 1.0
#P org.eclipse.jdt.core.tests.model
Index: src/org/eclipse/jdt/core/tests/model/JavaProjectTests.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/model/JavaProjectTests.java,v
retrieving revision 1.66
diff -u -r1.66 JavaProjectTests.java
--- src/org/eclipse/jdt/core/tests/model/JavaProjectTests.java	29 Mar 2006 04:03:07 -0000	1.66
+++ src/org/eclipse/jdt/core/tests/model/JavaProjectTests.java	3 May 2006 20:59:08 -0000
@@ -620,6 +620,44 @@
 	assertTrue("java should have subpackages",					java.hasSubpackages());
 	assertTrue("java.lang  should NOT have subpackages",			!lang.hasSubpackages());
 }
+/*
+ * Ensures that the structure is known for a package fragment on the classpath.
+ */
+public void testPackageFragmentIsStructureKnown1() throws CoreException {
+	IPackageFragment pkg = getPackageFragment("JavaProjectTests", "", "x");
+	assertTrue("Structure of package 'x' should be known", pkg.isStructureKnown());
+}
+/*
+ * Ensures that asking if the structure is known for a package fragment outside the classpath throws a JavaModelException.
+ * (regression test for bug 138577 Package content disapear in package explorer)
+ */
+public void testPackageFragmentIsStructureKnown2() throws CoreException {
+	try {
+		createJavaProject("P");
+		createFolder("/P/pack");
+		IPackageFragment pkg = getPackage("/P/pack");
+		editFile(
+			"/P/.classpath",
+			"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" + 
+			"<classpath>\n" + 
+			"	<classpathentry excluding=\"pack/\" kind=\"src\" path=\"\"/>\n" + 
+			"	<classpathentry kind=\"output\" path=\"\"/>\n" + 
+			"</classpath>"
+		);
+		JavaModelException exception = null;
+		try {
+			pkg.isStructureKnown();
+		} catch (JavaModelException e) {
+			exception = e;
+		}
+		assertExceptionEquals(
+			"Unexpected exception", 
+			"pack [in <project root> [in P]] does not exist",
+			exception);
+	} finally {
+		deleteProject("P");
+	}
+}
 /**
  * Test getting the non-java resources from a package fragment.
  */
#P org.eclipse.jdt.core
Index: model/org/eclipse/jdt/internal/core/PackageFragment.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/PackageFragment.java,v
retrieving revision 1.77
diff -u -r1.77 PackageFragment.java
--- model/org/eclipse/jdt/internal/core/PackageFragment.java	29 Mar 2006 03:08:47 -0000	1.77
+++ model/org/eclipse/jdt/internal/core/PackageFragment.java	3 May 2006 20:59:14 -0000
@@ -65,8 +65,12 @@
 
 	// check whether this pkg can be opened
 	if (!underlyingResource.isAccessible()) throw newNotPresentException();
-
+	
+	// check that it is not excluded (https://bugs.eclipse.org/bugs/show_bug.cgi?id=138577)
 	int kind = getKind();
+	if (kind == IPackageFragmentRoot.K_SOURCE && Util.isExcluded(this)) 
+		throw newNotPresentException();
+
 
 	// add compilation units/class files from resources
 	HashSet vChildren = new HashSet();