Lazy init DefaultOutput, to break class loading circular dependency

Fixes #1910

Unfortunately I couldn't find a way to add a testcase for this without changing every test to run as a fork. Verified manually.

CHANGES

@@ -15,6 +15,10 @@ Release 1.16.1 [PENDING]
     again, causing errors when fetched.
     <https://github.com/jhy/jsoup/issues/1902>
 
+  * Bugfix: If the Document.OutputSettings class was initialized, and then Entities.escape(String) called, an NPE may be
+    thrown due to a class loading circular dependency.
+    <https://github.com/jhy/jsoup/issues/1910>
+
 Release 1.15.4 [18-Feb-2023]
   * Improvement: added the ability to escape CSS selectors (tags, IDs, classes) to match elements that don't follow
     regular CSS syntax. For example, to match by classname <p class="one.two">, use document.select("p.one\\.two");

src/main/java/org/jsoup/nodes/Entities.java

@@ -7,6 +7,7 @@
 import org.jsoup.parser.CharacterReader;
 import org.jsoup.parser.Parser;
 
+import javax.annotation.Nullable;
 import java.io.IOException;
 import java.nio.charset.CharsetEncoder;
 import java.util.Arrays;
@@ -26,7 +27,6 @@ public class Entities {
     static final int codepointRadix = 36;
     private static final char[] codeDelims = {',', ';'};
     private static final HashMap<String, String> multipoints = new HashMap<>(); // name -> multiple character references
-    private static final OutputSettings DefaultOutput = new OutputSettings();
 
     public enum EscapeMode {
         /**
@@ -157,8 +157,11 @@ public static String escape(String string, OutputSettings out) {
      * @return the escaped string
      */
     public static String escape(String string) {
+        if (DefaultOutput == null)
+            DefaultOutput = new OutputSettings();
         return escape(string, DefaultOutput);
     }
+    private static @Nullable OutputSettings DefaultOutput; // lazy-init, to break circular dependency with OutputSettings
 
     // this method does a lot, but other breakups cause rescanning and stringbuilder generations
     static void escape(Appendable accum, String string, OutputSettings out,