Bug 183918 get relative file path of linkage library
model/org.eclipse.birt.report.model.tests/test/org/eclipse/birt/report/model/library/DesignLoadLibraryTest.java
{
			designHandle.includeLibrary( "Library_1.xml", "Lib1" ); 
			fail( );
		}
		catch ( Exception e )
		{
			assertTrue( e instanceof LibraryException );
			assertEquals(
					LibraryException.DESIGN_EXCEPTION_DUPLICATE_LIBRARY_NAMESPACE,
					( (LibraryException) e ).getErrorCode( ) );
		}
	}