The fix for
RESTEASY-1080 introduced another bug. If the DataSourceProvider uses a temporary file and the InputStream returned by getInputStream() is read until the end, any further call to getInputStream() results in a FileNotFoundException.
The SequenceDataSource used in the DataSourceProvider deletes the temporary file when it has been read until the end. When getInputStream() is called after the temporary file has been deleted new FileInputStream(tempFile) in getInputStream() results in a FileNotFoundException.
The javadoc of javax.activation.DataSource.getInputStream() however states:
... Note that a new InputStream object must be returned each time this method is called, and the stream must be positioned at the beginning of the data.