Upgrade to AssertJ 2.5.0

Closes gh-6473

spring-boot-dependencies/pom.xml

@@ -48,7 +48,7 @@
 		<appengine.version>1.9.40</appengine.version>
 		<artemis.version>1.3.0</artemis.version>
 		<aspectj.version>1.8.9</aspectj.version>
-		<assertj.version>2.4.1</assertj.version>
+		<assertj.version>2.5.0</assertj.version>
 		<atomikos.version>3.9.3</atomikos.version>
 		<bitronix.version>2.1.4</bitronix.version>
 		<caffeine.version>2.3.1</caffeine.version>

spring-boot-test/src/main/java/org/springframework/boot/test/json/JsonContentAssert.java

@@ -30,6 +30,7 @@ import org.assertj.core.api.AbstractMapAssert;
 import org.assertj.core.api.AbstractObjectAssert;
 import org.assertj.core.api.Assert;
 import org.assertj.core.api.Assertions;
+import org.assertj.core.api.ObjectAssert;
 import org.skyscreamer.jsonassert.JSONCompare;
 import org.skyscreamer.jsonassert.JSONCompareMode;
 import org.skyscreamer.jsonassert.JSONCompareResult;
@@ -935,7 +936,7 @@ public class JsonContentAssert extends AbstractAssert<JsonContentAssert, CharSeq
 	 * @throws AssertionError if the path is not valid or does not result in an array
 	 */
 	@SuppressWarnings("unchecked")
-	public AbstractListAssert<?, ?, Object> extractingJsonPathArrayValue(
+	public AbstractListAssert<?, ?, Object, ObjectAssert<Object>> extractingJsonPathArrayValue(
 			CharSequence expression, Object... args) {
 		return Assertions.assertThat(
 				extractingJsonPathValue(expression, args, List.class, "an array"));