FULL PRODUCT VERSION :
JDK 8u291

ADDITIONAL OS VERSION INFORMATION :
MS Windows 10 OS

A DESCRIPTION OF THE PROBLEM :
When French AZERTY keyboard layout is used, some characters cannot be entered by pressing key combinations involving "Alt Gr" key, which is also know as "Alt Graph" key, in a text editor in Oracle JDeveloper "12.2.1.4.0" application. For example the left curly bracket " { " cannot be entered by pressing the key combination "Alt Gr" + "4". The issue is reproducible, when Oracle JDeveloper application is executed by JDK from JDK 8 release family, and it is not reproducible, if JDK from JDK 11 release family is used.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Install French AZERTY keyboard layout in the OS. On Windows 10 OS:
"Start" -> "Windows System" -> "Control Panel" -> "Language" -> "Add a language" -> "French" -> "Open" -> "French (France)" -> "Add"
2. Install Oracle JDeveloper "12.2.1.4.0" product.
3. Run the installed Oracle JDeveloper application, select "Java EE Developer" and click "OK", create a new Java Application Project:
"File" -> "New" -> "Project..." -> "Java Project" -> "OK" -> "Finish"
4. In the created Java Project create a new Java Class:
"Right click on the created project" -> "New" -> "Java Class..." -> "OK"
5. Enable in the OS French keyboard layout.
6. In Oracle JDeveloper application in the source code editor of the created new Java class try to enter " { " by pressing the key combination "Alt Gr" + "4". The issue is reproduced, if the character is not entered in the source code editor window.

Please note that despite of the fact that " { " character cannot be entered, at the same time the character " } " can be successfully entered by pressing the key combination "Alt Gr" + "+".