JdkToolchainUtil: command built by string concat breaks on spaced java path; no timeout

`JdkToolchainUtil.getJavaVersion(Toolchain)` (line 40) builds the command by string concatenation:

```java
Commandline cl = new Commandline(java + " -version");
```

`Commandline` tokenizes the string on whitespace, so a `java` binary path containing spaces (common on Windows and macOS, e.g. `/Applications/My Tools/jdk/bin/java`) is split into multiple arguments and the command fails.

Additionally, `CommandLineUtils.executeCommandLine` is invoked without a timeout, so a hung JVM blocks the build indefinitely.

Suggested fix: use `cl.createArg().setValue(java)` / `cl.addArgument` and bound the command execution with a timeout.

Start at JdkToolchainUtil.getJavaVersion(Toolchain), around line 40, and inspect how Commandline and CommandLineUtils.executeCommandLine are used. The change is done when Java paths containing spaces remain one argument and a hung JVM is bounded by a timeout; no test file is named in the issue.

Written by the indexing model from the issue text.