private String getRandomBoundary() {
        return BOUNDARY_PREFIX + UUID.randomUUID();
    }
Generates a random boundary using UUID. The UUID is a v4 random UUID generated from a cryptographically-secure
random source.
<p>
A cryptographically-secure random number source is used to generate the UUID, to avoid a malicious actor crafting
a body part that contains the boundary value to tamper with the entity structure.
</p>
httpclient5/src/main/java/org/apache/hc/client5/http/entity/mime/MultipartEntityBuilder.java