We have detected that the data displayed in the report showing Jenkins, do not correspond exactly to the data in the file generated by Cobertura (coverage.xml).
There are differences in both total number of lines of the project, the number of lines covered and also in number of classes.

For example,

The content of the file coverage.xml for a specific build is the next one:

<coverage line-rate="0.21086464463558172" branch-rate="0.09980237154150198" lines-covered="2329" lines-valid="11045" branches-covered="303" branches-valid="3036" complexity="2.743722304283604" version="1.9.2" timestamp="1366727626987">

But the report of coverage shown in the Jenkins project, indicates that there are a total of 11023 Java lines and a total of 153 Java classes.

As you can see, the data is different