Passing parameters to results in struts2 does not work - struts2

Question

I have configured result as follows : Its my custom result type.
<result-types>
<result-type name="myBytesResult" class="blahblah.MyBytesResult" />
</result-types>
<action name="myAction" class="blahblah.MyAction">
<result name="success" type="myBytesResult">
<param name="pptId">${pptId}</param>
</result>
</action>
And my result has setter/getter for pptId and MyAction also has setter/getter for pptId. But when i check in my result, Its not setting pptId (I am getting ${pptId} as string in result). It seems its not getting getter from Action.
What could be reason for the same ?
The code MyAction
public String doDefault() {
System.out.println("Default Called");
setPptId("MyPpt");
return "success";
}
public byte[] getMyImageInBytes() throws Exception {
try {
//.....
} catch (Exception e) {
}
return null;
}
public String getContentType() {
return contentType;
}
public void setContentType(String contentType) {
this.contentType = contentType;
}
public String getPptId() {
return this.pptId;
}
public void setPptId(String pptId) {
this.pptId = pptId;
}
MyBytesResult
private String contentType;
private String pptId;
public void execute(ActionInvocation invocation) throws Exception {
HttpServletResponse response = ServletActionContext.getResponse();
//...Some more code for settign response
System.out.println("pt Id[" + this.pptId + "]");
}
public String getContentType() {
return contentType;
}
public void setContentType(String contentType) {
this.contentType = contentType;
}
public String getPptId() {
return pptId;
}
public void setPptId(String pptId) {
this.pptId = pptId;
}

Answer 1

Updated answer
So, after some digging, it appears that this is actually working properly. It is the responsibility of the Result to evaluate the incoming data as an OGNL expression if that is necessary. This is how the redirect and http header results work. You can parse the value against the stack in your custom result as follows:
String resolvedPptId = TextParseUtil.translateVariables(pptId, stack)
From the Javadoc for translateVariables:
Converts all instances of ${...}, and %{...} in expression to the value returned by a call to {#link ValueStack#findValue(java.lang.String)}. If an item cannot
be found on the stack (null is returned), then the entire variable ${...} is not
displayed, just as if the item was on the stack but returned an empty string.