You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: _response_specification.rs
    path of file: ./repos/aws-sdk-rust/sdk/lexmodelsv2/src/types
    
    the code of the file until where you have to start completion: // Code generated by software.amazon.smithy.rust.codegen.smithy-rs. DO NOT EDIT.

/// <p>Specifies a list of message groups that Amazon Lex uses to respond the user input.</p>
#[non_exhaustive]
#[derive(::std::clone::Clone, ::std::cmp::PartialEq, ::std::fmt::Debug)]
pub struct ResponseSpecification {
    /// <p>A collection of responses that Amazon Lex can send to the user. Amazon Lex chooses the actual response to send at runtime.</p>
    pub message_groups: ::std::vec::Vec<crate::types::MessageGroup>,
    /// <p>I
    
    pub fn build(self) -> ::std::result::Result<crate::types::ResponseSpecification, ::aws_smithy_types::error::operation::BuildError> {
        ::std::result::Result::Ok(crate::types::ResponseSpecification {
            message_groups: self.message_groups.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "message_groups",
                    "message_groups was not specified but it is required when building ResponseSpecification",
                )
            })?,
            allow_interrupt: self.allow_interrupt,
        })
    }