org.apache.pdfbox.util.PDFTextStripper class initialization throws NumberFormatException with recent Verona-enabled Java 9 JVMs

Lucene/Solr runs its whole testsuite also with Java 9 EA releases to trigger bugs early. In our tests (Solr + TIKA) we found out that org.apache.pdfbox.util.PDFTextStripper throws a NumberFormatException in its static initializer when parsing the "java.version" system property. The reason for failure is a change in Java 9, where version numbers got a new format.

There are 3 problems:

• It should not assume that all components are really a number. So it should try/catch NumberFormatException and assign some "unknown" version
• The code should really use "java.specification.version". This is standardized and only contains digits.
• The code should also be prepared to handle version numbers without minor version! E.g. Java 9 only has "9" instead of "1.9" as its main version number.

For the use case I would nuke this check and find a better workaround.

Relying on String parsing for non-standardized system properties in a static class initializer is the reason why this bug is raised to level "Critical".