ClangFormat experimental plugin: SortIncludes option does not works

Steps to reproduce:

• set QTC_FORMAT_INSTEAD_OF_INDENT environment variable to 1
• enable ClangFormat (experimental) plugin
• restart Qt Creator
• use code sample

#include <string>
#include <iostream>

using std::string;using std::endl;using std::cout;

int main(int,char*[]){cout<<string("hello, world")<<endl;return 0;}

• create .clang-format inside project directory

  BasedOnStyle: Google
  
  AccessModifierOffset: -4
  AlignAfterOpenBracket: Align
  AllowShortFunctionsOnASingleLine: None
  AllowShortIfStatementsOnASingleLine: false
  AllowShortLoopsOnASingleLine: false
  BraceWrapping: 
    AfterClass:      true
    AfterControlStatement: true
    AfterEnum:       true
    AfterFunction:   true
    AfterNamespace:  false
    AfterStruct:     true
    AfterUnion:      true
    AfterExternBlock: true
    BeforeCatch:     true
    BeforeElse:      true
    SplitEmptyFunction: false
    SplitEmptyRecord: true
    SplitEmptyNamespace: true
  BreakBeforeBraces: Custom
  BreakConstructorInitializers: BeforeColon
  ColumnLimit:     90
  ConstructorInitializerAllOnOneLineOrOnePerLine: false
  ContinuationIndentWidth: 8
  DerivePointerAlignment: false
  IndentCaseLabels: false
  IndentWidth:     4
  SpacesBeforeTrailingComments: 1
  Standard:        Cpp11
  

• select all (Crtl+A)
• auto-indent selection (Ctrl+I)

Expected result:

#include <iostream>
#include <string>

using std::cout;
using std::endl;
using std::string;

int main(int, char*[])
{
    cout << string("hello, world") << endl;
    return 0;
}

Actual result:

#include <string> // [ISSUE] not sorted
#include <iostream>

using std::cout; // [OK] sorted
using std::endl;
using std::string;

int main(int, char*[]) // [OK] reformatted
{
    cout << string("hello, world") << endl;
    return 0;
}