package "xlsx" unusable after having used package "xlconnect"

[TillF]

Because of complementary functionality I want to use "xlsx" after package "xlconnect".
However, the code snippet, which works when issued alone, fails when executed after having used "xlconnect" in the same session.

#A: usage of XLConnect ####
library(XLConnect)
wb <- XLConnect::loadWorkbook(file = paste0(tempfile(),".xlsx"), create = TRUE)  #create an empty xlsx 
# unload package and its dependencies
try(detach("package:XLConnect", unload=TRUE, force = TRUE), silent = TRUE)
try(detach("package:XLConnectJars", unload=TRUE, force = TRUE), silent = TRUE)
try(detach("package:rJava", unload=TRUE, force = TRUE), silent = TRUE)


#B: usage of xlsx ####
library(xlsx)
wb <- createWorkbook()
cs <- CellStyle(wb) +        #create a cell style
  Font(wb, heightInPoints=20) + 
  Fill(backgroundColor="lavender")
-> error

Error message:

Error in .jcall(cellStyle, "V", "setFillPattern", .jshort(CS[fill$pattern])) : method setFillPattern with signature (S)V not found

There is a complementary error when using the packages in the reverse order (miraisolutions/xlconnect#79).

Is there a workaround for this except restarting R?

sessionInfo()
R version 3.5.0 (2018-04-23)
Platform: i386-w64-mingw32/i386 (32-bit)
Running under: Windows 7 x64 (build 7601) Service Pack 1
Matrix products: default
locale:
[1] LC_COLLATE=German_Germany.1252 LC_CTYPE=German_Germany.1252
[3] LC_MONETARY=German_Germany.1252 LC_NUMERIC=C
[5] LC_TIME=German_Germany.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
loaded via a namespace (and not attached):
[1] compiler_3.5.0 rJava_0.9-9

[colearendt]

As the related issue suggests, this is not something that is supported. Both packages are trying to use the same underlying Java library and therefore have some conflicts.