Set the OpenAPI
                basePath property
In OpenAPI 2.0basePath property to provide one
            or more path parts that precede each path defined in the paths property.
            Because API Gateway has several ways to express a resource's path, the Import API feature
            provides the following options for interpreting the basePath property
            during import: ignore, prepend, and split.
In OpenAPI 3.0basePath is no longer a
            top-level property. Instead, API Gateway uses a server variable
- 
                If the API doesn't contain any basePathvariables, the Import API feature checks theserver.urlstring to see if it contains a path beyond"/". If it does, that path is used as the base path.
- 
                If the API contains only one basePathvariable, the Import API feature uses it as the base path, even if it's not referenced in theserver.url.
- 
                If the API contains multiple basePathvariables, the Import API feature uses only the first one as the base path.
Ignore
If the OpenAPI file has a basePath value of /a/b/c and
                the paths property contains /e and /f, the
                following POST or PUT request: 
POST /restapis?mode=import&basepath=ignore
PUT /restapis/api_id?basepath=ignore
results in the following resources in the API:
- 
                    /
- 
                    /e
- 
                    /f
 The effect is to treat the basePath as if it was not present, and all of the declared API resources are served relative to the
                host. This can be used, for example, when you have a custom domain name with an API mapping that doesn't include a Base
                    Path and a Stage value that refers to your production stage. 
Note
API Gateway automatically creates a root resource for you, even if it isn't explicitly declared in your definition file.
 When unspecified, basePath takes ignore by default.
            
Prepend
 If the OpenAPI file has a basePath value of
                    /a/b/c and the paths property contains /e
                and /f, the following POST or PUT request: 
POST /restapis?mode=import&basepath=prepend
PUT /restapis/api_id?basepath=prepend
results in the following resources in the API:
- 
                    /
- 
                    /a
- 
                    /a/b
- 
                    /a/b/c
- 
                    /a/b/c/e
- 
                    /a/b/c/f
 The effect is to treat the basePath as specifying additional
                resources (without methods) and to add them to the declared resource set. This can
                be used, for example, when different teams are responsible for different parts of an
                API and the basePath could reference the path location for each team's
                API part. 
Note
API Gateway automatically creates intermediate resources for you, even if they aren't explicitly declared in your definition.
Split
 If the OpenAPI file has a basePath value of
                    /a/b/c and the paths property contains /e
                and /f, the following POST or PUT request: 
POST /restapis?mode=import&basepath=split
PUT /restapis/api_id?basepath=split
results in the following resources in the API:
- 
                    /
- 
                    /b
- 
                    /b/c
- 
                    /b/c/e
- 
                    /b/c/f
 The effect is to treat top-most path part, /a, as the beginning of
                each resource's path, and to create additional (no method) resources within the API
                itself. This could, for example, be used when a is a stage name that
                you want to expose as part of your API.