Here are the most likely possibilities:
The release included several critical updates across different platforms, including Windows, macOS, Linux, and ARM architectures: JDK for ARM 8 Update 251 Release Notes - Oracle java 251
In the world of software development, "Java 251" isn't a version of the language itself, but rather a ghostly calling card found in —the long lists of code references that appear when a program crashes. Here are the most likely possibilities: The release