Use String.contains instead of indexOf != -1

Change-Id: I71865b70f8fac577dad6a256e59ea1b6568d807e
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.releng/+/190480
Reviewed-by: Alexander Kurtakov <akurtako@redhat.com>
Tested-by: Platform Bot <platform-bot@eclipse.org>
diff --git a/bundles/org.eclipse.releng.tests/src/org/eclipse/releng/tests/BuildTests.java b/bundles/org.eclipse.releng.tests/src/org/eclipse/releng/tests/BuildTests.java
index 07a7f11..fb09bbf 100644
--- a/bundles/org.eclipse.releng.tests/src/org/eclipse/releng/tests/BuildTests.java
+++ b/bundles/org.eclipse.releng.tests/src/org/eclipse/releng/tests/BuildTests.java
@@ -745,8 +745,8 @@
 					String tmp;
 					while ((tmp = in.readLine()) != null) {
 						tmp = tmp.toLowerCase();
-						if (tmp.indexOf(JAVADOC_ERROR) != -1 || tmp.indexOf(JAVADOC_WARNING) != -1
-								|| tmp.indexOf(JAVADOC_JAVA) != -1) {
+						if (tmp.contains(JAVADOC_ERROR) || tmp.contains(JAVADOC_WARNING)
+								|| tmp.contains(JAVADOC_JAVA)) {
 							String fileName = new File(javadocLog.getFile()).getName();
 							if (!logs.contains(fileName))
 								logs.add(fileName);