WINDUPRULE-665 Implemented multiple attempts approach

pom.xml

@@ -196,6 +196,12 @@
             <version>1.7.30</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.awaitility</groupId>
+            <artifactId>awaitility</artifactId>
+            <version>4.0.3</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <profiles>
@@ -306,7 +312,6 @@
                     <argLine>${arguments}</argLine>
                     <excludes>
                         <exclude>**/WindupRulesMultipleTests*</exclude>
-                        <exclude>**/WindupRulesLinksTest*</exclude>
                     </excludes>
                	</configuration>
             </plugin>

src/test/java/org/jboss/windup/rules/tests/WindupRulesLinksTest.java

@@ -1,6 +1,7 @@
 package org.jboss.windup.rules.tests;
 
 import org.apache.commons.lang3.StringUtils;
+import org.awaitility.core.ConditionTimeoutException;
 import org.jboss.windup.util.file.FileSuffixPredicate;
 import org.jboss.windup.util.file.FileVisit;
 import org.junit.AfterClass;
@@ -22,6 +23,8 @@
 import java.net.HttpURLConnection;
 import java.net.URL;
 import java.nio.file.Path;
+import java.time.Duration;
+import java.time.temporal.ChronoUnit;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -33,6 +36,8 @@
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 
+import static org.awaitility.Awaitility.with;
+
 /**
  * This tests all the href attribute in ALL the rules every time the tests are executed (PR and nightly builds)
  * Helpful to ensure we have always links that points to something so that links are really helpful for the user
@@ -43,13 +48,23 @@
  * To change the connection timeout use the standard "-Dsun.net.client.defaultConnectTimeout=<value>" property
  * from https://docs.oracle.com/javase/8/docs/technotes/guides/net/properties.html
  * 
+ * The default poll interval for the same link in case of connection timeout is 200 milliseconds.
+ * To change it use the property "-DpollInterval=<value>" with <value> specified in milliseconds.
+ * 
+ * The default poll duration for the same link in case of connection timeout is 30000 milliseconds.
+ * To change it use the property "-DpollAtMost=<value>" with <value> specified in milliseconds.
+ * 
  * To quickly see the debug log, execute the test with the property "-Dorg.slf4j.simpleLogger.log.org.jboss.windup=debug"
  */
 @RunWith(Parameterized.class)
 public class WindupRulesLinksTest {
 
     private static final Logger LOG = LoggerFactory.getLogger(WindupRulesLinksTest.class);
     private static final String RUN_TEST_MATCHING = "runTestsMatching";
+    private static final String LINK_POLL_INTERVAL = "pollInterval";
+    private static final Duration LINK_POLL_INTERVAL_DURATION = Duration.of(Long.getLong(LINK_POLL_INTERVAL, 200L), ChronoUnit.MILLIS);
+    private static final String LINK_POLL_AT_MOST = "pollAtMost";
+    private static final Duration LINK_POLL_AT_MOST_DURATION = Duration.of(Long.getLong(LINK_POLL_AT_MOST, 30000L), ChronoUnit.MILLIS);
     private static final List<Integer> ACCEPTED_RESPONSE_CODE = Arrays.asList(
             HttpURLConnection.HTTP_OK,
             HttpURLConnection.HTTP_MOVED_PERM,
@@ -152,14 +167,29 @@ private boolean isValidLink(final String link)
                 final HttpURLConnection urlConn = (HttpURLConnection) url.openConnection();
                 // property name from https://docs.oracle.com/javase/8/docs/technotes/guides/net/properties.html
                 urlConn.setConnectTimeout(Integer.getInteger("sun.net.client.defaultConnectTimeout", 5000));
-                urlConn.connect();
+                with()
+                    .pollDelay(Duration.ZERO)
+                    .pollInterval(LINK_POLL_INTERVAL_DURATION)
+                    .await()
+                    .atMost(LINK_POLL_AT_MOST_DURATION)
+                    .until(() -> {
+                        try {
+                            urlConn.connect();
+                            return true;
+                        } catch (IOException e) {
+                            LOG.warn(String.format("'%s' exception connecting to %s", e.getMessage(), link));
+                            return false;
+                        } finally {
+                            urlConn.disconnect();
+                        }
+                    });
                 CACHE_ANALYZED_LINKS.put(link, urlConn.getResponseCode());
             }
             final boolean validLink = ACCEPTED_RESPONSE_CODE.contains(CACHE_ANALYZED_LINKS.get(link));
             if (validLink) LOG.debug(String.format("Response code %d for %s [%dms]", CACHE_ANALYZED_LINKS.get(link), link, System.currentTimeMillis() - starTime));
             else LOG.error(String.format("Response code %d for %s [%dms]", CACHE_ANALYZED_LINKS.get(link), link, System.currentTimeMillis() - starTime));
             return validLink;
-        } catch (IOException e) {
+        } catch (IOException | ConditionTimeoutException e) {
             LOG.error(String.format("'%s' exception connecting to %s", e.getMessage(), link));
             return false;
         }