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: _time_window.rs
    path of file: ./repos/aws-sdk-rust/sdk/wafv2/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>In a <code>GetSampledRequests</code> request, the <code>StartTime</code> and <code>EndTime</code> objects specify the time range for which you want WAF to return a sample of web requests.</p>
/// <p>You must specify the times in Coordinated Universal Time (UTC) format. UTC format includes the special designator, <code>Z</code>. For example, <code>"2016-09-27T14:50Z"</code>. You can specify any time range in the previous three hours.</p>
/// <p>In a
    
    pub fn build(self) -> ::std::result::Result<crate::types::TimeWindow, ::aws_smithy_types::error::operation::BuildError> {
        ::std::result::Result::Ok(crate::types::TimeWindow {
            start_time: self.start_time.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "start_time",
                    "start_time was not specified but it is required when building TimeWindow",
                )
            })?,
            end_time: self.end_time.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "end_time",
                    "end_time was not specified but it is required when building TimeWindow",
                )
            })?,
        })
    }