Exception on get mapping for type

[raidersv]

Exception message "Could not create an instance of type Nest.ISourceFieldMapping. Type is an interface or abstract class and cannot be instantiated." during a call "ElasticClient.GetMapping" function.

Some properties in class "public class RootObjectMapping : ObjectMapping" have interface type and can't be instantiated, example:
[JsonProperty("_source")]
public ISourceFieldMapping SourceFieldMappingDescriptor { get; set; }

[gmarz]

@raidersv this is actually a known bug and has been fixed by @johndaniels in #829. We plan on releasing 1.0.1 soon. Thanks for reporting.