QT how to pass Enum to EnumHelper correctly - qt

Question

I have found a helper class for enums (EnumHelper) to convert enums to strings and strings to enums.
I want to use this class in another class (MyEnums) in which I define different enums and want to provide a ToString() and FromString() method for each enum type.
If I try to convert an enum from a third class (Test) I get an error message that I don't understand.
EnumHelper.h
#pragma once
#include <QMetaEnum>
template <typename E>
class EnumHelper
{
public:
EnumHelper();
QString toString(E value);
};
EnumHelper.cpp
#include "EnumHelper.h"
template<typename E>
EnumHelper<E>::EnumHelper()
{
}
template<typename E>
QString EnumHelper<E>::toString(E value)
{
const int retval = static_cast<int>(value);
return QString::fromUtf8(QMetaEnum::fromType<E>().valueToKey(retval));
}
MyEnums.h
#pragma once
#include <QObject>
#include "EnumHelper.h"
class ColorNameEnums
{
Q_GADGET
public:
enum Value {
White,
Grey,
LightGrey,
DarkerGrey,
DarkGrey,
Mint,
DarkMint,
Red,
DarkRed,
Black,
Blue
};
Q_ENUM(Value)
private:
explicit ColorNameEnums();
};
class MyEnums : QObject
{
public:
explicit MyEnums(QObject* parent = nullptr);
QString colorNameToString(ColorNameEnums value);
ColorNameEnums colorNameFromString(QString value);
private:
EnumHelper<ColorNameEnums> m_colorName;
};
MyEnums.cpp
#include "MyEnums.h"
MyEnums::MyEnums(QObject* parent)
{
}
QString MyEnums::colorNameToString(ColorNameEnums value) { return m_colorName.toString(value); }
ColorNameEnums MyEnums::colorNameFromString(QString value) { return m_colorName.fromString(value); }
Test.h
#pragma once
#include <QObject>
#include "MyEnums.h"
class Test : public QObject
{
Q_OBJECT
public:
explicit Test(QObject* parent = nullptr);
private:
MyEnums* m_enums = new MyEnums();
};
Test.cpp
#include "Test.h"
Test::Test(QObject* parent)
{
}
void Test::test()
{
auto xx = m_enums->colorNameToString(ColorNameEnums::White);
}
Error is:
For a conversion of ""ColorNameEnums::Value"" to""ColorNameEnums"" no suitable constructor is available.