Map to object where properties are in a single associative array

Nobody has claimed this yet.

Hey there,

I was wondering if there was an easy way to map to a destination object where all the properties are in a single associative array?

For example

```
class Employee
{
private $id;
private $firstName;
private $lastName;
private $birthYear;

public function __construct($id, $firstName, $lastName, $birthYear)
{
$this->id = $id;
$this->firstName = $firstName;
$this->lastName = $lastName;
$this->birthYear = $birthYear;
}

public function getId()
{
return $this->id;
}

// And so on...
}
```

and MapTo

```
class EmployeeEntity
{
private $_propDict = [];

public function getId()
{
return $_propDict['id'] ?? null;
}

public function setId($val)
{
$_propDict['id'] = $val;
}

// And so on...
}
```

The issue does not name a source file, test, or entry point. Start by tracing the existing MapTo mapping API and how destination properties are assigned; define expected behavior for EmployeeEntity's $_propDict representation, then add coverage for the example.

Written by the indexing model from the issue text.