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: _header_order.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>Inspect a string containing the list of the request's header names, ordered as they appear in the web request that WAF receives for inspection. WAF generates the string and then uses that as the field to match component in its inspection. WAF separates the header names in the string using co
    
    pub fn build(self) -> ::std::result::Result<crate::types::HeaderOrder, ::aws_smithy_types::error::operation::BuildError> {
        ::std::result::Result::Ok(crate::types::HeaderOrder {
            oversize_handling: self.oversize_handling.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "oversize_handling",
                    "oversize_handling was not specified but it is required when building HeaderOrder",
                )
            })?,
        })
    }