RFR: 8265909 : build.tools.dtdbuilder.DTDBuilder.java failed detecting missing path of dtd_home [v2]

[ScientificWare]

> This concerns [dtdbuilder tools](https://github.com/openjdk/jdk/tree/master/make/jdk/src/classes/build/tools/dtdbuilder).
> 
> In jshell, try `System.getProperty("html32") + ""` you'll get a `String`.
> 
> So, in `DTDBuilder.java` when none `dtd_home` property is set, the `dtd_home` string value is not `null`, causing an exception with the present test.
> 
> The expected value is `"Must set property 'dtd_home'"`
> 
> And in this case, should'nt we have a `System.exit(1)` too rather than a simple `return` ?

ScientificWare has updated the pull request incrementally with one additional commit since the last revision:

  Changes to keep home_dtd null check.
  
  As suggested in conversation moving `+ File.separator` is more elegant than changing the `null` check.

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3626/files
  - new: https://git.openjdk.java.net/jdk/pull/3626/files/94c97f14..d1a6727e

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3626&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3626&range=00-01

  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3626.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3626/head:pull/3626

PR: https://git.openjdk.java.net/jdk/pull/3626