When connecting to Informix using the Informix JDBC driver you may get the following exception:

java.lang.ClassNotFoundException: org.bson.BSONObject
  at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:471)
  at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:588)
  at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)

The root cause of this is that for some versions (verified on 4.50.2) of the JDBC Driver a dependant JAR file is missing. The missing jar file must be added to the Informix driver entry using the Driver Manager in DbVisualizer.

The missing bson jar file can be downloaded from this Maven repository.  It is typically named, bson-<version>.jar such as bson-3.11.1.jar.