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: _primary.rs
    path of file: ./repos/aws-sdk-rust/sdk/eventbridge/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>The primary Region of the endpoint.</p>
#[non_exhaustive]
#[derive(::std::clone::Clone, ::std::cmp::PartialEq, ::std::fmt::Debug)]
pub struct Primary {
    /// <p>The ARN of the health check used by the endpoint to determine whether 
    
    pub fn build(self) -> ::std::result::Result<crate::types::Primary, ::aws_smithy_types::error::operation::BuildError> {
        ::std::result::Result::Ok(crate::types::Primary {
            health_check: self.health_check.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "health_check",
                    "health_check was not specified but it is required when building Primary",
                )
            })?,
        })
    }