udpate versions (pom and property) in the same run

If versions:set and versions:set-property are launched in separate
maven commands, versions:set-property can fail as poms are in an
inconsistent state.

Attached test case shows a practical use-case where a property is used
in dependencyManagement declaration in a multi-module project.

If project is not installed, versions:set-property 1.0.1-SNAPSHOT ->
1.0.1 fails as maven tries to resolve dependency 1.0.1-SNAPSHOT in a
project already versionned in 1.0.1.

Author: lalmeras

src/main/java/com/amashchenko/maven/plugin/gitflow/AbstractGitFlowMojo.java

@@ -1017,15 +1017,26 @@ protected void mvnSetVersions(final String version) throws MojoFailureException,
 
             executeMvnCommand(TYCHO_VERSIONS_PLUGIN_SET_GOAL, prop, newVersion, "-Dtycho.mode=maven");
         } else {
+            boolean runCommand = false;
+            List<String> args = new ArrayList<>();
+            args.add("-DgenerateBackupPoms=false");
+            args.add(newVersion);
             if (!skipUpdateVersion) {
-                executeMvnCommand(VERSIONS_MAVEN_PLUGIN_SET_GOAL, grp, art, newVersion, "-DgenerateBackupPoms=false");
+                runCommand = true;
+                args.add(VERSIONS_MAVEN_PLUGIN_SET_GOAL);
+                args.add(grp);
+                args.add(art);
             }
 
             if (StringUtils.isNotBlank(versionProperty)) {
+                runCommand = true;
                 getLog().info("Updating property '" + versionProperty + "' to '" + version + "'.");
 
-                executeMvnCommand(VERSIONS_MAVEN_PLUGIN_SET_PROPERTY_GOAL, newVersion, "-Dproperty=" + versionProperty,
-                        "-DgenerateBackupPoms=false");
+                args.add(VERSIONS_MAVEN_PLUGIN_SET_PROPERTY_GOAL);
+                args.add("-Dproperty=" + versionProperty);
+            }
+            if (runCommand) {
+                executeMvnCommand(args.toArray(new String[0]));
             }
         }
     }