Problem with fix URI prefixes with overlapping prefix names

[cjmyers]

The error below happens when uploading to changing URI prefix for a document that includes overlapping URI prefixes like:

https://www.first/
https://www.second/

Error: java.lang.IllegalArgumentException: Unable to set default URI prefix to non-compliant value `https://www./'
at org.sbolstandard.core2.SBOLDocument.setDefaultURIprefix(SBOLDocument.java:4474)
at org.sbolstandard.core2.SBOLDocument.fixDocumentURIPrefix(SBOLDocument.java:2363)
at org.sbolstandard.core2.SBOLDocument.changeURIPrefixVersion(SBOLDocument.java:2865)