Update PropertySourcesPlaceholderConfigurer.java

Fix the error message when PropertySources are not applied

spring-context/src/main/java/org/springframework/context/support/PropertySourcesPlaceholderConfigurer.java

@@ -202,7 +202,7 @@ public class PropertySourcesPlaceholderConfigurer extends PlaceholderConfigurerS
 	 * @since 4.0
 	 */
 	public PropertySources getAppliedPropertySources() throws IllegalStateException {
-		Assert.state(this.appliedPropertySources != null, "PropertySources have not get been applied");
+		Assert.state(this.appliedPropertySources != null, "PropertySources have not yet been applied");
 		return this.appliedPropertySources;
 	}