Eclipse-Formatter-Plugin fails due to wrong assumptions

The Eclipse-Plugin has sometimes a problem when I call the formatter programatically inside Eclipse. I am using the Snippet from https://help.eclipse.org/latest/topic/org.eclipse.jdt.doc.isv/guide/jdt_api_codeformatter.htm to format a complete Java-File. I have created a minimal Test-Class:

```
package test;

/**
* Test Class
*
* Generated
*
*/
public class Test
{
}
```
The standalone-Formatter-Jar adds a HTML-Tag

before the "Generated". Unfortunately, when I call the plugin via the Eclipse-APIs:
```java
final TextEdit edit =
codeFormatter.format(
CodeFormatter.K_COMPILATION_UNIT, // format a compilation unit
content, // source to format
0, // starting position
content.length(), // length
0, // initial indentation
"\r\n" // line separator
);
```
the method returns a null because it can not format the content. I have tracked the problem back to the class SnippetFormatter.java, Method toReplacements(). This method has the condition which checks the unformatted and the formatted source:
```java
if (!NOT_WHITESPACE.retainFrom(source).equals(NOT_WHITESPACE.retainFrom(replacement))) {
throw new IllegalArgumentException(
"source = \"" + source + "\", replacement = \"" + replacement + "\"");
}
```
This condition checks that there are only whitespace-changes in the new formatted source. The Javadoc says:
```quote
under the assumption that they differ in whitespace alone.
```
Unfortunately, this assumption is not correct. The source has (as mentioned above) an additional non-whitespace change and the IllegalArgumentException is thrown. This Exception causes the Eclipse-Formatter-Class to fail and to return only null, thereby denying to format the source.