Fix broken Javadoc link targets

[ctrueden]

[WARNING] javadoc: warning - Error fetching URL: https://imagej.net/ij/developer/api/
[WARNING] javadoc: warning - Error fetching URL: https://javadoc.scijava.org/MorphoLibJ/
[WARNING] javadoc: warning - Error fetching URL: https://help.eclipse.org/latest/nftopic/org.eclipse.platform.doc.isv/reference/api/
[WARNING] javadoc: warning - Error fetching URL: https://javadoc.scijava.org/JGraphT/
[WARNING] javadoc: warning - Error fetching URL: https://javadoc.scijava.org/JOML/
[WARNING] javadoc: warning - Error fetching URL: https://javadoc.scijava.org/Javassist/

[ctrueden]

Would be obviated by scijava/pom-scijava#130