ignoreImportProviders property doesn't allow multiple values.

[Simon Gaeremynck]

The ignoreImportProviders property as defined on [1] states that you can 
specify multiple readers you wish to ignore.
For example:

SLING-INF/content;overwrite=true;ignoreImportProviders:=xml,json


AFAICT it only chooses the first one.
I've traced this down to the ManifestHeader class in o.a.s.commons.osgi. 
It looks like it interprets the comma between xml and json as a seperator of 
Attributes instead of a seperator of Values.

The following test in ManifestHeaderTest identifies this issue:


public void testMultiple() {
      String header = 
"SLING-INF/content/etc;overwrite=true;ignoreImportProviders=json,xml";
      final ManifestHeader entry = ManifestHeader.parse(header);
      assertEquals("json,xml", 
entry.getEntries()[0].getAttributes()[1].getValue());
    }

Regards,
Simon

[1] 
http://sling.apache.org/site/content-loading-jcrcontentloader.html#ContentLoading(jcr.contentloader)-Extractors