[MNG-7131] maven.config doesn't handle arguments with spaces in them

Since we don't have a clear specification of the file format change
reading of the file to a one-arg-per-line basis just like Java's
@argfiles or Python's argparse would handle it.
Consider that jvm.config suffers from the same issue its parsing is not
portable between Bourne shell and Windows Command prompt.

maven-embedder/src/main/java/org/apache/maven/cli/MavenCli.java

@@ -104,6 +104,7 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.PrintStream;
+import java.nio.charset.Charset;
 import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -387,7 +388,7 @@ public class MavenCli
 
             if ( configFile.isFile() )
             {
-                for ( String arg : new String( Files.readAllBytes( configFile.toPath() ) ).split( "\\s+" ) )
+                for ( String arg : Files.readAllLines( configFile.toPath(), Charset.defaultCharset() ) )
                 {
                     if ( !arg.isEmpty() )
                     {

maven-embedder/src/test/java/org/apache/maven/cli/MavenCliTest.java

@@ -195,8 +195,10 @@ public class MavenCliTest
     /**
      * Read .mvn/maven.config with the following definitions:
      * <pre>
-     *   -T 3
+     *   -T
+     *   3
      *   -Drevision=1.3.0
+     *   "-Dlabel=Apache Maven"
      * </pre>
      * and check if the {@code -T 3} option can be overwritten via command line
      * argument.
@@ -221,8 +223,10 @@ public class MavenCliTest
     /**
      * Read .mvn/maven.config with the following definitions:
      * <pre>
-     *   -T 3
+     *   -T
+     *   3
      *   -Drevision=1.3.0
+     *   "-Dlabel=Apache Maven"
      * </pre>
      * and check if the {@code -Drevision-1.3.0} option can be overwritten via command line
      * argument.
@@ -249,8 +253,10 @@ public class MavenCliTest
     /**
      * Read .mvn/maven.config with the following definitions:
      * <pre>
-     *   -T 3
+     *   -T
+     *   3
      *   -Drevision=1.3.0
+     *   "-Dlabel=Apache Maven"
      * </pre>
      * and check if the {@code -Drevision-1.3.0} option can be overwritten via command line
      * argument.
@@ -277,8 +283,10 @@ public class MavenCliTest
     /**
      * Read .mvn/maven.config with the following definitions:
      * <pre>
-     *   -T 3
+     *   -T
+     *   3
      *   -Drevision=1.3.0
+     *   "-Dlabel=Apache Maven"
      * </pre>
      * and check if the {@code -Drevision-1.3.0} option can be overwritten via command line argument when there are
      * funky arguments present.
@@ -300,11 +308,14 @@ public class MavenCliTest
         cli.cli( request );
         cli.properties( request );
 
+        assertEquals( "3", request.commandLine.getOptionValue( CLIManager.THREADS ) );
+
         String revision = System.getProperty( "revision" );
         assertEquals( "8.2.0", revision );
 
         assertEquals( "bar ", request.getSystemProperties().getProperty( "foo" ) );
         assertEquals( "bar two", request.getSystemProperties().getProperty( "foo2" ) );
+        assertEquals( "Apache Maven", request.getSystemProperties().getProperty( "label" ) );
 
         assertEquals( "-Dpom.xml", request.getCommandLine().getOptionValue( CLIManager.ALTERNATE_POM_FILE ) );
     }

maven-embedder/src/test/projects/config/.mvn/maven.config

@@ -1,2 +1,3 @@
--T8 --builder  
+-T8
-  multithreaded
+--builder
+multithreaded

maven-embedder/src/test/projects/mavenConfigProperties/.mvn/maven.config

@@ -1,3 +1,5 @@
--T 3
+-T
+3
 -Drevision=1.3.0
+"-Dlabel=Apache Maven"