FormDataBodyPart type handling inconsistency

I think that the type handling in com.sun.jersey.multipart.FormDataBodyPart is inconsistent. We noticed this issue with jersey-multipart-1.16.0.jar but it still exists in 1.19.

We noticed the issue with "Content-Type: text/plain; charset=US-ASCII" as compared to "Content-Type: text/plain".

The issue is related to the comparisons against MediaType.TEXT_PLAIN_TYPE. In 2 places it is a direct comparison: setValue() and isSimple(). In the other location it is a clever comparison: getValue().

I think it would be better if isSimple() was coded as:

public boolean isSimple()

{ return MediaTypes.typeEquals(MediaType.TEXT_PLAIN_TYPE, getMediaType()); }

and that setValue() and getValue() used the isSimple() method.
#### Affected Versions
[1.19.2]