feature: allowEmptyValue controls (#4788)

* add baseline tests

* coerce empty strings to null when updating parameter values

* add ParameterIncludeEmpty

* add redux management for empty parameter value inclusion state

* use name+in keying for state management instead of hash keying

* update new redux method usages to name+in keying

* coerce empty Immutable iterables in onChangeWrapper

* OAS3 tests & support

* add included empty parameters to requests before dispatching to Swagger Client

* make empty inclusion interface prettier

* add tests for #4587

* linter fixes

* check for truthy value before reaching into property

src/core/presets/base.js

@@ -42,6 +42,7 @@ import Response from "core/components/response"
 import ResponseBody from "core/components/response-body"
 import Parameters from "core/components/parameters"
 import ParameterExt from "core/components/parameter-extension"
+import ParameterIncludeEmpty from "core/components/parameter-include-empty"
 import ParameterRow from "core/components/parameter-row"
 import Execute from "core/components/execute"
 import Headers from "core/components/headers"
@@ -143,6 +144,7 @@ export default function() {
       OperationExt,
       OperationExtRow,
       ParameterExt,
+      ParameterIncludeEmpty,
       OperationTag,
       OperationContainer,
       DeepLink,