Nest driver can't create include: "" element in the aggregations

[wolczas]

Elasticsearch version: 5.2.2

OS version: Win 10

Description of the problem including expected versus actual behavior:
include section in the aggregation is unable to create a simple string inside of terms.

I want to create

"catpaths": {
          "terms": {
            "field": "categories.categoryPath",
           "include": "(/[^/]+){2}"
          },

Using Nest statements include value gets wrapped in [] and pattern elements:

• TermsAggregationDescriptor<T> Include(string includePattern, string regexFlags = null);
  Nest:
        .Include(@"(/[^/]+){2}*","")
  DSL:
         "include":{"pattern":"(/[^/]+){2}"}}

• TermsAggregationDescriptor<T> Include(IEnumerable<string> values)
  Nest:
        var sequence = Enumerable.Repeat("(/[^/]+){2}", 1);
        .Include(sequence)
  DSL:
        "include": ["(/[^/]+){2}"]

I need a Nest TermsAggregationDescriptor include statement that will generate string DSL:
             "include": "(/[^/]+){2}"

Extra pattern element prevents parser to continue with evaluating nested aggs.
Array of include [] uses literal strings and does not evaluate elements regex expression.

[russcam]

Thanks for submitting @wolczas; this is a bug 🐛 that will be addressed in the next release.

[gmarz]

Closed via #2693