When mixing periods and dollar signs in a logger name, an IllegalArgumentException is thrown from LoggerFactory.getLogger:

scala> org.slf4j.LoggerFactory.getLogger("a.b$c.d")
java.lang.IllegalArgumentException: For logger [a] child name [a.b$c passed as parameter, may not include '.' after index2
at ch.qos.logback.classic.Logger.createChildByName(Logger.java:386)
at ch.qos.logback.classic.LoggerContext.getLogger(LoggerContext.java:152)
at ch.qos.logback.classic.LoggerContext.getLogger(LoggerContext.java:48)
at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:253)

Note that the following works:
scala> org.slf4j.LoggerFactory.getLogger("a$b.c")
res0: org.slf4j.Logger = Logger[a$b.c]