Fix queriedMethods handling in ReflectionHintsSerializer

[sdeleuze]

As discovered by @snicoll, serialiation of queriedMethods is broken when there is no methods.

[
  {
    "name": "com.example.nativex.sample.basic.SampleConfiguration"
    "queriedMethods": [
      {
        "name": "testBean",
        "parameterTypes": []
      }
    ]
  }
]