[Formatter] Javadoc formatter sometimes incorrectly encodes `@` to `@` inside {@code} blocks

[ryanpinter]

The formatter incorrectly encodes certain @ symbols that are included in <pre> {@code javadoc blocks. I am not sure the rules for encoding the @ on annotations, it doesn't appear to break anything but encoding it on a {@code does break the javadoc rendering.

Possibly related to: #2071

Reproduction Input:

  /**
   * Example showing formatter bug with {@code @} in pre blocks.
   *
   * <pre>
   * {@code
   * @MyAnnotation
   * public class Example {
   *
   *     @AnotherAnnotation
   *     private String field;
   * }
   * }
   * </pre>
   */
  public interface ExampleService {

      /**
       * Another method with annotation in javadoc.
       *
       * <pre>
       * {@code
       * @Override
       * public void doSomething() {
       *     // implementation
       * }
       * }
       * </pre>
       */
      void doSomething();
  }

---

With "Enable Classic Javadoc formatting" : False
With "Format Java code snippets inside 'pre' tags": False
Result: No Change

---

With "Enable Classic Javadoc formatting" : True
With "Format Java code snippets inside 'pre' tags": False
Result: @'s on some Annotations are converted to @

/**
 * Example showing formatter bug with {@code @} in pre blocks.
 *
 * <pre>
 * {@code
 * &#64;MyAnnotation     <--- Possible error
 * public class Example {
 *
 *     @AnotherAnnotation    <--- Why did this not get encoded
 *     private String field;
 * }
 * }
 * </pre>
 */
public interface ExampleService {
	/**
	 * Another method with annotation in javadoc.
	 *
	 * <pre>
	 * {@code
	 * &#64;Override    <--- Possible error
	 * public void doSomething() {
	 *     // implementation
	 * }
	 * }
	 * </pre>
	 */
	void doSomething();
}

---

With "Enable Classic Javadoc formatting" : True
With "Format Java code snippets inside 'pre' tags": True
Result: @'s on some Annotations and some {@code are converted to @

/**
 * Example showing formatter bug with {@code @} in pre blocks.
 *
 * <pre>
 * {
 * 	&#64;code    <--- Definitive error
 * 	&#64;MyAnnotation
 * 	public class Example {
 * 		@AnotherAnnotation
 * 		private String field;
 * 	}
 * }
 * </pre>
 */
public interface ExampleService {
	/**
	 * Another method with annotation in javadoc.
	 *
	 * <pre>
	 * {@code
	 * @Override
	 * public void doSomething() {
	 * 	// implementation
	 * }
	 * }
	 * </pre>
	 */
	void doSomething();
}

[subyssurendran666]

Definitely it is related to #2071 . This issue will be resolved once #4851 is merged into master.

[SougandhS]

I believe this one is bit different from #4851 (pure-snippet, no html tag) and need to be fixed separately as the given example is from inside <pre>. hence re-opening