[regression] Compilation issues for the missing imports are not highlighting for the copy paste java code

The compilation issues for the missing imports are not highlighting for the copy-paste java code.

Environment

• Operating System: Windows 10
• JDK version: Java 1.8.0_231
• Visual Studio Code version: 1.45.1
• Java extension version: 0.91

Steps To Reproduce

1. Copy-paste a simple java program without imports (For Example I copy-pasted the code Calendar cal = Calendar.getInstance();)
2. Verify that the compilation issue is not highlighted for the missing import of the class Calendar.

Note:

1. We can easily correct it for small programs but it will be difficult for the big programs since we can identify the import missing issue only when we run the program.