Webfiles with underscores in filename fail to import

Webfiles with two underscores '_' in its filename will not get imported, but will trigger an exception. If this occurs during bootstrapping, the exception will cause the bootstrapping of the webfiles to stop, so no webfiles are bootstrapped. See example stacktrace below.

Any filename that starts with an underscore and then has another underscore later in the filename but not right after the first one – will trigger an error. So _f_oo or foo, but not __foo or f_o_o.
 
Example stacktrace:
[*INFO*] [talledLocalContainer] Caused by: javax.jcr.NamespaceException: ui-v4004-common-js-libs-Visitor: is not a registered namespace prefix.

[*INFO*] [talledLocalContainer] at org.apache.jackrabbit.core.NamespaceRegistryImpl.getURI(NamespaceRegistryImpl.java:478) ~[jackrabbit-core-2.14.0-h1.jar:2.14.0-h1]