Restore quotes around module detection JAVA_HOME

[headius]

See #6615 (review)

The quoting around $JAVA_HOME was inadvertently removed while fixing module detection in #6615. The review linked above points out that this causes problems when the JDK is installed in a path with spaces. This is not common on unixy environments, and the bash script is not used on Windows where it is more common, but the regression is real.

This PR restores the quoting around $JAVA_HOME to fix the issue.

[headius]

According to @walro in #6615 (comment) the affected path with spaces is where Oracle JDK 8 installed on MacOS (/Library/Internet Something). This differs from where my system installs, in /LIbrary/Java/JavaVirtualMachines and may indicate a new layout for JDKs in newer MacOS releases.

I have asked for more information.

[walro]

Thanks!

I noticed this since I, for reasons I do not remember now, had my $JAVA_HOME pointing at /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home. It's the "JRE path" of Oracle's Java installation, see for example:

• https://docs.oracle.com/javase/8/docs/technotes/guides/install/mac_jre.html#A1097025
• https://docs.oracle.com/javase/9/install/installation-jdk-and-jre-macos.htm#JSJIG-GUID-5F4A0659-BFC5-4CB9-9920-D2DEABF29894
• https://docs.oracle.com/javase/10/install/installed-directory-structure-jdk-and-jre.htm#JSJIG-GUID-F7178F2F-DC92-47E9-8062-CA6B2612D350

[walro]

indicate a new layout for JDKs in newer MacOS releases.

I think it has been like this "forever", I might just be odd favoring a JRE installation (I generally don't do any Java development) ;-)

[headius]

@walro Aha that explains it! We should run fine with a JRE so that is no problem, but I did not realize that the Oracle JRE gets installed in a path with spaces (and referencing the long-deprecated Applet feature, no less!)

I will look into adding a test for this situation, at least when on MacOS and such a path is available.