Added conditionals to "build_" GHA workflows so that they only run wh…

…en needed

.github/workflows/build_linux_client.yml

@@ -74,13 +74,19 @@ jobs:
             
   build:
     needs: changes    
-    uses: ./.github/workflows/build_linux.yml  
+    uses: ./.github/workflows/build_linux.yml
+
+    # Only run this if the changes job actually detected changes OR if we are building all.
+    # Empty array will be serialized as [] so you can simply check it in the if condition.
+    # Second part of the condition just checks if it's not an empty string - that would mean some failure during changes job execution.
+    if: ${{ (!inputs.buildAll && needs.changes.outputs.BEAMPROJS != '[]' && needs.changes.outputs.BEAMPROJS != '') || inputs.buildAll }}
+
     strategy:
       max-parallel: 1
       matrix:
+        # Result of changes job as well as vars are plain strings. That's why you have to use fromJson() to parse it into array.
         # The list of BeamProj is defined by "wherever we detected changes" when inputs.buildAll is false
-        # The list of BeamProj is a hard-coded list of all BeamProjs when inputs.buildAll is true
-        # This is because our RC job also reuses this but needs to generate ALL builds independent of changes. 
+        # The list of BeamProj is Repository Variable (declared in Github's UnrealSDK's Settings -> Secrets & Variables -> Variables).         
         beamProj: ${{ !inputs.buildAll && fromJSON(needs.changes.outputs.BEAMPROJS) || fromJSON(vars.ALL_BEAMPROJS) }}
     with:
       beamProj: ${{ matrix.beamProj }}

.github/workflows/build_linux_server.yml

@@ -53,10 +53,17 @@ jobs:
   
   build:
     needs: changes
-    uses: ./.github/workflows/build_linux.yml
+    uses: ./.github/workflows/build_linux.yml    
+
+    # Only run this if the changes job actually detected changes OR if we are building all.
+    # Empty array will be serialized as [] so you can simply check it in the if condition.
+    # Second part of the condition just checks if it's not an empty string - that would mean some failure during changes job execution.
+    if: ${{ (!inputs.buildAll && needs.changes.outputs.BEAMPROJS != '[]' && needs.changes.outputs.BEAMPROJS != '') || inputs.buildAll }}
+
     strategy:
       max-parallel: 1
       matrix:
+        # Result of changes job as well as vars are plain strings. That's why you have to use fromJson() to parse it into array.
         # The list of BeamProj is defined by "wherever we detected changes" when inputs.buildAll is false
         # The list of BeamProj is Repository Variable (declared in Github's UnrealSDK's Settings -> Secrets & Variables -> Variables).        
         beamProj: ${{ !inputs.buildAll && fromJSON(needs.changes.outputs.BEAMPROJS) || fromJSON(vars.ALL_SERVER_BEAMPROJS) }}    

.github/workflows/build_windows_client.yml

@@ -78,12 +78,18 @@ jobs:
             
   build:
     uses: ./.github/workflows/build_windows.yml
+
+    # Only run this if the changes job actually detected changes OR if we are building all.
+    # Empty array will be serialized as [] so you can simply check it in the if condition.
+    # Second part of the condition just checks if it's not an empty string - that would mean some failure during changes job execution.
+    if: ${{ (!inputs.buildAll && needs.changes.outputs.BEAMPROJS != '[]' && needs.changes.outputs.BEAMPROJS != '') || inputs.buildAll }}
+
     strategy:
       max-parallel: 2
       matrix:
+        # Result of changes job as well as vars are plain strings. That's why you have to use fromJson() to parse it into array.
         # The list of BeamProj is defined by "wherever we detected changes" when inputs.buildAll is false
-        # The list of BeamProj is a hard-coded list of all BeamProjs when inputs.buildAll is true
-        # This is because our RC job also reuses this but needs to generate ALL builds independent of changes. 
+        # The list of BeamProj is Repository Variable (declared in Github's UnrealSDK's Settings -> Secrets & Variables -> Variables).         
         beamProj: ${{ !inputs.buildAll && fromJSON(needs.changes.outputs.BEAMPROJS) || fromJSON(vars.ALL_BEAMPROJS) }}
     with:
       beamProj: ${{ matrix.beamProj }}