rPackages.rJava: set JAVA_HOME, fixes darwin (#355931)

Author: jbedo

pkgs/development/r-modules/default.nix

@@ -1286,6 +1286,10 @@ let
       preConfigure = ''
         export JAVA_CPPFLAGS=-I${pkgs.jdk}/include/
         export JAVA_HOME=${pkgs.jdk}
+        substituteInPlace R/zzz.R.in \
+          --replace-fail ".onLoad <- function(libname, pkgname) {" \
+            ".onLoad <- function(libname, pkgname) {
+             Sys.setenv(\"JAVA_HOME\" = Sys.getenv(\"JAVA_HOME\", unset = \"${pkgs.jdk}\"))"
       '';
     });