Formatter repeatedly adds <p> tags to @code blocks inside Javadoc

The formatter repeatedly adds

tags to items inside an \@code block in Javadoc.

Expected: consistent output when the formatter is run repeatedly
Impact: Difficulty adding the formatter to our CI

```
$ cat Example.java

package com.foo.bar;

/**
* {@code public enum MyFile {
*
*

// A cool new thing
*
* } }
*/

$ java -jar google-java-format-1.5-all-deps.jar -i Example.java
$ cat Example.java

package com.foo.bar;

/**
* {@code public enum MyFile {
*
*

// A cool new thing
*
*

} }
*/

$ java -jar google-java-format-1.5-all-deps.jar -i Example.java
$ cat Example.java
package com.foo.bar;

/**
* {@code public enum MyFile {
*
*

// A cool new thing
*
*

} }
*/
```