PDFBox 1.6.0 (but also the latest released versions) have a bug with Java 7: PDFBOX-1512.
The only workaround is to avoid using the new Java 7 sort methods and fall back to the legacy ones. This must be added to nuxeo.conf:
-Djava.util.Arrays.useLegacyMergeSort=true
See also http://answers.nuxeo.com/questions/6323/search-inside-pdf