fix #420: fix detection of java version when JAVA_TOOL_OPTIONS is set

Author: glhez

.gitignore

@@ -6,3 +6,4 @@ bin
 .idea
 *.iml
 .java-version
+*.bak

plexus-compilers/plexus-compiler-javac/src/main/java/org/codehaus/plexus/compiler/javac/JavacCompiler.java

@@ -259,16 +259,17 @@ private String getOutOfProcessJavacVersion(String executable) throws CompilerExc
              */
             cli.addArguments(new String[] {"-version"}); //
             CommandLineUtils.StringStreamConsumer out = new CommandLineUtils.StringStreamConsumer();
+            CommandLineUtils.StringStreamConsumer err = new CommandLineUtils.StringStreamConsumer();
             try {
-                int exitCode = CommandLineUtils.executeCommandLine(cli, out, out);
+                int exitCode = CommandLineUtils.executeCommandLine(cli, out, err);
                 if (exitCode != 0) {
                     throw new CompilerException("Could not retrieve version from " + executable + ". Exit code "
-                            + exitCode + ", Output: " + out.getOutput());
+                            + exitCode + ", Output: " + out.getOutput() + ", Error: " + err.getOutput());
                 }
             } catch (CommandLineException e) {
                 throw new CompilerException("Error while executing the external compiler " + executable, e);
             }
-            version = extractMajorAndMinorVersion(out.getOutput());
+            version = tryParseVersion(out.getOutput().trim());
             VERSION_PER_EXECUTABLE.put(executable, version);
         }
         return version;
@@ -282,6 +283,19 @@ static String extractMajorAndMinorVersion(String text) {
         return matcher.group();
     }
 
+    private String tryParseVersion(String version) {
+        if (version.startsWith("javac ")) {
+            version = version.substring(6);
+            if (version.startsWith("1.")) {
+                version = version.substring(0, 3);
+            } else {
+                version = version.substring(0, 2);
+            }
+            return version;
+        }
+        return null;
+    }
+
     @Override
     public CompilerResult performCompile(CompilerConfiguration config) throws CompilerException {
         File destinationDir = new File(config.getOutputLocation());

plexus-compilers/plexus-compiler-javac/src/test/java/org/codehaus/plexus/compiler/javac/JavacCompilerTest.java

@@ -121,5 +121,6 @@ void testExtractMajorAndMinorVersion() {
         assertEquals("11.0", JavacCompiler.extractMajorAndMinorVersion("javac 11.0.22"));
         assertEquals("11.0", JavacCompiler.extractMajorAndMinorVersion("11.0.22"));
         assertEquals("21", JavacCompiler.extractMajorAndMinorVersion("javac 21"));
+        assertEquals("1.8", JavacCompiler.extractMajorAndMinorVersion("javac 1.8.0_432"));
     }
 }