Android Retrofit2 calls to aspnet webapi are not triggering post when @SerializedName is added, but not passing object w/o it

Question

I am trying to POST to a dotnet webapi from android retrofit. When I POST an object I am getting to the controller (I see the log entries in the console), but no values are getting passed. When I add @SerializedName, as I have had to do in other calls, the call is not even triggering the webapi controller post method.

My webapi controller looks like this:

    [HttpPost]
    public async Task<ActionResult<PageResults<TokenExchangeDTO>>> Post([FromBody] SearchFilter searchFilter) 
    {
        _logger.LogDebug("Debug Post");
        _logger.LogDebug("Post called: SearchPhrase=" + searchFilter.SearchPhrase + 
                            ";PageNumber=" + searchFilter.PageNumber + ";PageSize=" + searchFilter.PageSize);

        return Ok(await Search(searchFilter));
    }

I am trying to use this object as the input for the call:

public class PagingSearchDto {

     @SerializedName("searchPhrase")
     private String searchPhrase;
     @SerializedName("pageNumber")
     private int pageNumber;
     @SerializedName("pageSize")
     private int pageSize;

     public void setSearchPhrase (String searchPhrase) { this.searchPhrase=searchPhrase; }
     public String getSearchPhrase() { return this.searchPhrase; }

     public void setPageNumber (int pageNumber) { this.pageNumber=pageNumber; }
     public int getPageNumber() { return this.pageNumber; }

     public void setPageSize(int pageSize) { this.pageSize=pageSize; }
     public int getPageSize() { return this.pageSize; }

}

When I comment out the @SerializedName statements I can see the aspnet logging statements, but the object values are empty. When I add @SerializedName it looks like they don't get triggered at all.

I can see there is a request of some sort as I have ApplicationInsights on the dotnet webapi, so the request is seemingly made.

I have another POST working and set this one up in the exact same manner and this seems like strange behavior and hard to diagnose. I am following all the documentation and even have a working example in another POST.

I have an interceptor and see the post looks like this:

[PagingSearchDto{searchPhrase='', pageNumber=1, pageSize=10}]

I wish I could make it this to test:

{searchPhrase='', pageNumber=1, pageSize=10}

Is there any way to control how the json at the class level?