To solve this problem, you need to create a reflection-config.json file which has the following content

[
  {
    "name": "software.amazon.cloudwatchlogs.emf.model.RootNode",
    "allDeclaredConstructors":true,
    "allPublicConstructors":true,
    "allDeclaredMethods":true,
    "allPublicMethods":true,
    "allDeclaredFields":true,
    "allPublicFields":true
  },
  {
    "name": "software.amazon.cloudwatchlogs.emf.model.Metadata",
    "allDeclaredConstructors":true,
    "allPublicConstructors":true,
    "allDeclaredMethods":true,
    "allPublicMethods":true,
    "allDeclaredFields":true,
    "allPublicFields":true
  },
  {
    "name": "software.amazon.cloudwatchlogs.emf.model.MetricDefinition",
    "allDeclaredConstructors":true,
    "allPublicConstructors":true,
    "allDeclaredMethods":true,
    "allPublicMethods":true,
    "allDeclaredFields":true,
    "allPublicFields":true
  },
  {
    "name": "software.amazon.cloudwatchlogs.emf.model.Unit",
    "allDeclaredConstructors":true,
    "allPublicConstructors":true,
    "allDeclaredMethods":true,
    "allPublicMethods":true,
    "allDeclaredFields":true,
    "allPublicFields":true
  },
  {
    "name": "software.amazon.cloudwatchlogs.emf.model.StorageResolution",
    "allDeclaredConstructors":true,
    "allPublicConstructors":true,
    "allDeclaredMethods":true,
    "allPublicMethods":true,
    "allDeclaredFields":true,
    "allPublicFields":true
  },
  {
    "name": "software.amazon.cloudwatchlogs.emf.model.DimensionSet",
    "allDeclaredConstructors":true,
    "allPublicConstructors":true,
    "allDeclaredMethods":true,
    "allPublicMethods":true,
    "allDeclaredFields":true,
    "allPublicFields":true
  },
  {
    "name": "software.amazon.cloudwatchlogs.emf.model.EmptyMetricsFilter",
    "allDeclaredConstructors":true,
    "allPublicConstructors":true,
    "allDeclaredMethods":true,
    "allPublicMethods":true,
    "allDeclaredFields":true,
    "allPublicFields":true
  },
  {
    "name": "software.amazon.cloudwatchlogs.emf.model.MetricDirective",
    "allDeclaredConstructors":true,
    "allPublicConstructors":true,
    "allDeclaredMethods":true,
    "allPublicMethods":true,
    "allDeclaredFields":true,
    "allPublicFields":true
  },
  {
    "name": "software.amazon.cloudwatchlogs.emf.model.MetricsContext",
    "allDeclaredConstructors":true,
    "allPublicConstructors":true,
    "allDeclaredMethods":true,
    "allPublicMethods":true,
    "allDeclaredFields":true,
    "allPublicFields":true
  },
  {
    "name": "software.amazon.cloudwatchlogs.emf.serializers.InstantSerializer",
    "allDeclaredConstructors":true,
    "allPublicConstructors":true,
    "allDeclaredMethods":true,
    "allPublicMethods":true,
    "allDeclaredFields":true,
    "allPublicFields":true
  },
  {
    "name": "software.amazon.cloudwatchlogs.emf.serializers.UnitSerializer",
    "allDeclaredConstructors":true,
    "allPublicConstructors":true,
    "allDeclaredMethods":true,
    "allPublicMethods":true,
    "allDeclaredFields":true,
    "allPublicFields":true
  },
  {
    "name": "software.amazon.cloudwatchlogs.emf.serializers.StorageResolutionSerializer",
    "allDeclaredConstructors":true,
    "allPublicConstructors":true,
    "allDeclaredMethods":true,
    "allPublicMethods":true,
    "allDeclaredFields":true,
    "allPublicFields":true
  },
  {
    "name": "software.amazon.cloudwatchlogs.emf.serializers.StorageResolutionFilter",
    "allDeclaredConstructors":true,
    "allPublicConstructors":true,
    "allDeclaredMethods":true,
    "allPublicMethods":true,
    "allDeclaredFields":true,
    "allPublicFields":true
  }
]

Basically, all the classes in software.amazon.cloudwatchlogs.emf.model and all the classes except the deserializers software.amazon.cloudwatchlogs.emf.serializers

Then, provide the argument -H:ReflectionConfigurationFiles=reflection-config.json to the native-image command line

Answer courtesy of @dan1st