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: _encryption_contract_configuration.rs
    path of file: ./repos/aws-sdk-rust/sdk/mediapackagev2/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>Configure one or more content encryption keys for your endpoints that use SPEKE Version 2.0. The encryption contract defines which content keys are used to encrypt the audio and video tracks in your stream. To config
    
    pub fn build(self) -> ::std::result::Result<crate::types::EncryptionContractConfiguration, ::aws_smithy_types::error::operation::BuildError> {
        ::std::result::Result::Ok(crate::types::EncryptionContractConfiguration {
            preset_speke20_audio: self.preset_speke20_audio.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "preset_speke20_audio",
                    "preset_speke20_audio was not specified but it is required when building EncryptionContractConfiguration",
                )
            })?,
            preset_speke20_video: self.preset_speke20_video.ok_or_else(|| {
                ::aws_smithy_types::error::operation::BuildError::missing_field(
                    "preset_speke20_video",
                    "preset_speke20_video was not specified but it is required when building EncryptionContractConfiguration",
                )
            })?,
        })
    }