licenseref-case-sensitive should be considered invalid

[vargenau]

case-sensitive4.spdx.txt

Java tools 1.1.8 considers the SPDX as valid.

However, in the line

PackageLicenseDeclared: licenseref-case-sensitive

licenseref-case-sensitive should be flagged as invalid.

Tools Python flags it as invalid:

 pyspdxtools -i case-sensitive4.spdx
ERROR:root:The document is invalid. The following issues have been found:
Unrecognized license reference: licenseref-case-sensitive. license_expression must only use IDs from the license list or extracted licensing info, but is: licenseref-case-sensitive

[goneall]

Once spdx/spdx-spec#984 is merged, we can update the library to flag these as invalid. It will require a minor amount of redesign, so it may be a while before I can get this fixed.