PutLifecycle invalid actions JSON

[lakario]

NEST/Elasticsearch.Net version: 7.4.0

Elasticsearch version: 7.4.x

Description of the problem including expected versus actual behavior:
The .NEST client does not create valid JSON for the actions of a PutLifecycle request. If more than one action is declared, there are no commas between the actions object members.

Steps to reproduce:

1. Create 7.4.0 ElasticClient
2. Call PutLifeycle with at least two actions for a single lifecycle phase

var client = new ElasticClient(new ConnectionSettings(new Uri("http://localhost:9200"))
		.DisableDirectStreaming());
	
var response = client.IndexLifecycleManagement.PutLifecycle(
	"policy1",
	pld => pld.Policy(pd => pd
		.Phases(phasesDesc => phasesDesc
			.Cold(phaseDesc => phaseDesc
				.Actions(actionsDesc => actionsDesc
					.Freeze(d => d)
					.SetPriority(d => d.Priority(50))
				)
			)
		)
	)
);

Provide ConnectionSettings (if relevant):
DisableDirectStreaming()

Provide DebugInformation (if relevant):

Invalid NEST response built from a unsuccessful (400) low level call on PUT: /_ilm/policy/policy1

Audit trail of this API call:

• [1] BadResponse: Node: http://localhost:9200/ Took: 00:00:00.0059976

OriginalException: Elasticsearch.Net.ElasticsearchClientException: The remote server returned an error: (400) Bad Request.. Call: Status code 400 from: PUT /_ilm/policy/policy1. ServerError: Type: x_content_parse_exception Reason: "[1:51] [put_lifecycle_request] failed to parse field [policy]" CausedBy: "Type: x_content_parse_exception Reason: "[1:51] [lifecycle_policy] failed to parse field [phases]" CausedBy: "Type: x_content_parse_exception Reason: "[1:51] [phases] failed to parse field [cold]" CausedBy: "Type: x_content_parse_exception Reason: "[1:51] [phase] failed to parse field [actions]" CausedBy: "Type: json_parse_exception Reason: "Unexpected character ('"' (code 34)): was expecting comma to separate Object entries

at [Source: org.elasticsearch.transport.netty4.ByteBufStreamInput@7750ef74; line: 1, column: 53]""""" ---> System.Net.WebException: The remote server returned an error: (400) Bad Request.
at System.Net.HttpWebRequest.GetResponse()
at Elasticsearch.Net.HttpWebRequestConnection.Request[TResponse](RequestData requestData)
--- End of inner exception stack trace ---

Request:

{"policy":{"phases":{"cold":{"actions":{"freeze":{}"set_priority":{"priority":50}}}}}}

Response:

{"error":{"root_cause":[{"type":"x_content_parse_exception","reason":"[1:51] [phase] failed to parse field [actions]"}],"type":"x_content_parse_exception","reason":"[1:51] [put_lifecycle_request] failed to parse field [policy]","caused_by":{"type":"x_content_parse_exception","reason":"[1:51] [lifecycle_policy] failed to parse field [phases]","caused_by":{"type":"x_content_parse_exception","reason":"[1:51] [phases] failed to parse field [cold]","caused_by":{"type":"x_content_parse_exception","reason":"[1:51] [phase] failed to parse field [actions]","caused_by":{"type":"json_parse_exception","reason":"Unexpected character ('"' (code 34)): was expecting comma to separate Object entries\n at [Source: org.elasticsearch.transport.netty4.ByteBufStreamInput@7750ef74; line: 1, column: 53]"}}}}},"status":400}

[russcam]

count should be incremented after serializing a value:

elasticsearch-net/src/Nest/XPack/Ilm/LifecycleActions.cs

Line 127 in c330114

var count = 0;