client-api/src/main/java/com/streamsets/datacollector/client/ApiClient.java
public String selectHeaderContentType(String[] contentTypes) {
    if (contentTypes.length == 0) return "application/json";
    if (StringUtil.containsIgnoreCase(contentTypes, "application/json")) return "application/json";
    return contentTypes[0];
  }
public String selectHeaderContentType(String[] contentTypes) {
    if (contentTypes.length == 0) return "application/json";
    if (StringUtil.containsIgnoreCase(contentTypes, "application/json")) return "application/json";
    return contentTypes[0];
  }
Select the Content-Type header's value from the given array:
if JSON exists in the given array, use it;
otherwise use the first one of the array.

@param contentTypes The Content-Type array to select from
@return The Content-Type header to use. If the given array is empty,
JSON will be used.