Data mesh is a decentralized data architecture that shifts the responsibility of managing data to data domains, allowing them to deliver domain-specific data as products tailored to meet customer needs. It promotes the idea of dynamically discovering and composing data products, forming a network of interacting data products. In this context, a key challenge is monitoring and regulating data exchanges between data products. To address this issue, data contracts have been proposed as formal agreements that define and enforce terms for exchanging data between producers and consumers. However, there is little academic literature on the topic, leaving a research gap in understanding it in detail. At the same time, since the data contract concept emerged from the industry, there is a considerable number of articles on it from practitioners, also known as gray literature. Hence, we conducted a systematic review of the gray literature on data contracts to clearly define the concept, identify the motivations for adopting it in organizations, develop guidelines for its implementation, and establish a research roadmap for further studies.