SWS-1036 - Make SimpleXsdSchema's toString more resilient

Backported to 2.x.

spring-xml/src/main/java/org/springframework/xml/xsd/SimpleXsdSchema.java

@@ -91,6 +91,9 @@ public class SimpleXsdSchema implements XsdSchema, InitializingBean {
 
 	@Override
 	public String getTargetNamespace() {
+
+		Assert.notNull(schemaElement, "schemaElement must not be null! Did you run afterPropertiesSet() or register this as a Spring bean?");
+		
 		return schemaElement.getAttribute("targetNamespace");
 	}
 

spring-xml/src/test/java/org/springframework/xml/xsd/SimpleXsdSchemaTest.java

@@ -16,6 +16,8 @@
 
 package org.springframework.xml.xsd;
 
+import org.junit.Test;
+
 import org.springframework.core.io.Resource;
 
 public class SimpleXsdSchemaTest extends AbstractXsdSchemaTestCase {
@@ -27,4 +29,11 @@ public class SimpleXsdSchemaTest extends AbstractXsdSchemaTestCase {
 		return schema;
 	}
 
+	@Test(expected = IllegalArgumentException.class)
+	public void testBareXsdSchema() {
+
+		SimpleXsdSchema schema = new SimpleXsdSchema();
+		schema.toString();
+	}
+
 }