Adding javadocs.

Author: dweiss

etc/junit4-missing-features.txt

@@ -26,3 +26,5 @@
 - can we enforce the order of extensions (randomized testing > leaked threads)
 - how are jupiter timeouts working together with leaked threads ext.?
 - maybe bring back thread leak zombies annotation (if we can't cleanly terminate leaked threads, ignore all remaining tests).
+- maybe move some of the implementation details to a non-exposed package?
+- regenerate the javadocs with public API only.

randomizedtesting-jupiter/src/main/java/com/carrotsearch/randomizedtesting/jupiter/Seed.java

@@ -1,5 +1,6 @@
 package com.carrotsearch.randomizedtesting.jupiter;
 
+/** A single randomization seed (typically part of a larger {@link SeedChain}). */
 public record Seed(long value) {
   private static final char[] HEX = "0123456789ABCDEF".toCharArray();
   static final Seed UNSPECIFIED = new Seed(0);

randomizedtesting-jupiter/src/main/java/com/carrotsearch/randomizedtesting/jupiter/SeedChain.java

@@ -2,11 +2,15 @@
 
 import java.util.List;
 import java.util.Locale;
-import java.util.Random;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-record SeedChain(List<Seed> seeds) {
+/**
+ * A seed chain determines randomization if {@link Randomized} extension is used. A seed chain is a
+ * sequence of {@link Seed}s, typically associated with one or more hierarchical junit jupiter
+ * contexts.
+ */
+public record SeedChain(List<Seed> seeds) {
   private static final SeedChain EMPTY = new SeedChain(List.of());
 
   static SeedChain parse(String chain) {
@@ -37,7 +41,7 @@ public String toString() {
 
   record FirstAndRest(Seed first, SeedChain rest) {}
 
-  public FirstAndRest pop() {
+  FirstAndRest pop() {
     if (seeds.isEmpty()) {
       return new FirstAndRest(Seed.UNSPECIFIED, SeedChain.EMPTY);
     }
@@ -46,8 +50,4 @@ public FirstAndRest pop() {
     var rest = new SeedChain(seeds.subList(1, seeds.size()));
     return new FirstAndRest(first, rest);
   }
-
-  private long nextRandomValue() {
-    return new Random().nextLong();
-  }
 }

randomizedtesting-jupiter/src/main/java/com/carrotsearch/randomizedtesting/jupiter/SystemThreadFilter.java

@@ -4,6 +4,9 @@
 import java.util.regex.Pattern;
 
 /**
+ * The default filter containing sane defaults excluding system and ignorable threads when {@link
+ * DetectThreadLeaks} extension is used.
+ *
  * @see DetectThreadLeaks.ExcludeThreads
  */
 public class SystemThreadFilter implements Predicate<Thread> {

randomizedtesting-jupiter/src/main/java/com/carrotsearch/randomizedtesting/jupiter/Threads.java

@@ -1,10 +1,10 @@
 package com.carrotsearch.randomizedtesting.jupiter;
 
-public final class Threads {
+final class Threads {
   Threads() {}
 
   /** Collect thread information, JVM vendor insensitive. */
-  public static String threadName(Thread t) {
+  static String threadName(Thread t) {
     return "Thread["
         + ("id=" + t.threadId())
         + (", name=" + t.getName())