Fix to cut extra elements from Java 11 serialization

Author: idodeclare

opengrok-indexer/src/main/java/org/opengrok/indexer/configuration/ConfigurationHelp.java

@@ -92,10 +92,15 @@ public static String getSamples() throws RuntimeException {
                     mthd);
             }
 
+            String propertyName = mthd.getName().replaceFirst("^set", "");
+
             sample = conf.getXMLRepresentationAsString();
             sample = sample.replaceFirst(
                 "(?sx)^<\\?xml.*Configuration\\d*\">\\n", "");
             sample = sample.replaceFirst("</object>\\n</java>", "");
+            // With Java 11 the following excision is necessary.
+            sample = sample.replaceFirst("(?isx)^.*\\n(?=\\s*<void\\s+property=\"" +
+                    propertyName + "\")", "");
 
             h.clear();
             h.append(XML_COMMENT_START);

opengrok-indexer/src/test/java/org/opengrok/indexer/configuration/ConfigurationHelpTest.java

@@ -18,11 +18,12 @@
  */
 
 /*
- * Copyright (c) 2018, Chris Fraire <cfraire@me.com>.
+ * Copyright (c) 2018, 2020, Chris Fraire <cfraire@me.com>.
  */
 
 package org.opengrok.indexer.configuration;
 
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 import org.junit.Test;
 
@@ -33,9 +34,12 @@ public class ConfigurationHelpTest {
     @Test
     public void shouldCreateReadableUsage() {
         String samples = ConfigurationHelp.getSamples();
-        assertTrue("samples are not empty", !samples.isEmpty());
+        assertFalse("samples are not empty", samples.isEmpty());
         assertTrue("samples contains \"<?\"", samples.contains("<?"));
         assertTrue("samples contains \"user-defined\"",
             samples.contains("user-defined"));
+        assertTrue("Java 11 nulls are removed",
+                samples.contains("<!-- Sample for setWebappCtags. Default is false -->\n" +
+                "  <void property=\"webappCtags\">\n"));
     }
 }