GitHubSanityCachedValue can block whole application

[alexec]

The GitHubSanityCachedValue class contains a single shaled lock. This means that client to this class can be blocked by another user of the function.

Instead, it might be better to use a read/write lock.

github-api/src/main/java/org/kohsuke/github/GitHubSanityCachedValue.java

Line 11 in 9e09d67

class GitHubSanityCachedValue<T> {