[Typescript, JSON Schema] No union type with anyOf

Using quicktype in combination with JSON Schema and typescript leads to the following issue:

_anyOf_ does not convert to a union type in some cases.

E.g.

```
{
"$ref": "#/definitions/TestObject",
"definitions": {
"TestObject": {
"type": "object",
"properties": {
"firstProperty": {
"anyOf": [{ "$ref": "#/definitions/MyObjectA" }, { "$ref": "#/definitions/MyObjectB" }]
},
"secondProperty": {
"anyOf": [
{ "type": "array", "items": { "$ref": "#/definitions/MyObjectA" } },
{
"$ref": "#/definitions/MyObjectB"
}
]
}
}
},
"MyObjectA": {
"type": "object",
"properties": {
"a": { "type": "string" },
"b": { "type": "number" },
"c": { "type": "boolean" }
}
},
"MyObjectB": {
"type": "object",
"properties": {
"d": { "type": "string" },
"e": { "type": "number" },
"f": { "type": "boolean" }
}
}
}
}
```

**Expected:**

```
export interface TestSchema {
firstProperty?: MyObjectA | MyObjectB;
secondProperty?: MyObjectA[] | MyObjectB;
}

export interface MyObjectA {
a?: string;
b?: number;
c?: boolean;
}

export interface MyObjectB {
d?: string;
e?: number;
f?: boolean;
}
```

**Actual result:**

```
export interface TestSchema {
firstProperty?: MyObject;
secondProperty?: MyObjectA[] | MyObjectB;
}

export interface MyObject {
a?: string;
b?: number;
c?: boolean;
d?: string;
e?: number;
f?: boolean;
}

export interface MyObjectA {
a?: string;
b?: number;
c?: boolean;
}

export interface MyObjectB {
d?: string;
e?: number;
f?: boolean;
}
```

The union in the _secondProperty_ (array with the object type) works as expected. However the union with the two object types generates a combined interface with a weaker type than the expected union type.