openjdk*: add meta.mainProgram

pkgs/development/compilers/openjdk/11.nix

@@ -142,6 +142,7 @@ let
       description = "The open-source Java Development Kit";
       maintainers = with maintainers; [ edwtjo asbachb ];
       platforms = [ "i686-linux" "x86_64-linux" "aarch64-linux" "armv7l-linux" "armv6l-linux" ];
+      mainProgram = "java";
     };
 
     passthru = {

pkgs/development/compilers/openjdk/12.nix

@@ -151,6 +151,7 @@ let
       description = "The open-source Java Development Kit";
       maintainers = with maintainers; [ edwtjo ];
       platforms = [ "i686-linux" "x86_64-linux" "aarch64-linux" "armv7l-linux" "armv6l-linux" ];
+      mainProgram = "java";
     };
 
     passthru = {

pkgs/development/compilers/openjdk/13.nix

@@ -151,6 +151,7 @@ let
       description = "The open-source Java Development Kit";
       maintainers = with maintainers; [ edwtjo ];
       platforms = [ "i686-linux" "x86_64-linux" "aarch64-linux" "armv7l-linux" "armv6l-linux" ];
+      mainProgram = "java";
     };
 
     passthru = {

pkgs/development/compilers/openjdk/14.nix

@@ -147,6 +147,7 @@ let
       description = "The open-source Java Development Kit";
       maintainers = with maintainers; [ edwtjo ];
       platforms = [ "i686-linux" "x86_64-linux" "aarch64-linux" "armv7l-linux" "armv6l-linux" ];
+      mainProgram = "java";
     };
 
     passthru = {

pkgs/development/compilers/openjdk/15.nix

@@ -147,6 +147,7 @@ let
       description = "The open-source Java Development Kit";
       maintainers = with maintainers; [ edwtjo ];
       platforms = [ "i686-linux" "x86_64-linux" "aarch64-linux" "armv7l-linux" "armv6l-linux" ];
+      mainProgram = "java";
     };
 
     passthru = {

pkgs/development/compilers/openjdk/16.nix

@@ -153,6 +153,7 @@ let
       description = "The open-source Java Development Kit";
       maintainers = with maintainers; [ edwtjo ];
       platforms = [ "i686-linux" "x86_64-linux" "aarch64-linux" "armv7l-linux" "armv6l-linux" ];
+      mainProgram = "java";
     };
 
     passthru = {

pkgs/development/compilers/openjdk/8.nix

@@ -262,6 +262,7 @@ let
       description = "The open-source Java Development Kit";
       maintainers = with maintainers; [ edwtjo ];
       platforms = [ "i686-linux" "x86_64-linux" "aarch64-linux" ];
+      mainProgram = "java";
     };
 
     passthru = {