Throw IllegalStateException from afterPropertiesSet

Consistently use Assert.state in the afterPropertiesSet()
methods to throw IllegalStateException instead of
IllegalArgumentException when some properties are missing
and/or invalid.

Resolves #2244

spring-batch-test/src/main/java/org/springframework/batch/test/DataSourceInitializer.java

@@ -107,7 +107,7 @@ public class DataSourceInitializer implements InitializingBean, DisposableBean {
 
 	@Override
 	public void afterPropertiesSet() {
-		Assert.notNull(this.dataSource, "A DataSource is required");
+		Assert.state(this.dataSource != null, "A DataSource is required");
 		initialize();
 	}