use detected start command when scheduling kpack droplets

- `@process.command` only covers commands set through the API
- `@process.started_command` is what we use when scheduling LRPs on BOSH
since it also includes detected start commands and commands from a
`Procfile`
- this worked before for the `web` process because the kpack-built
image's `Entrypoint` knows the detected start command -- it did not work
for multi-process apps, however

[#175081086](https://www.pivotaltracker.com/story/show/175081086)

Authored-by: Tim Downey <tdowney@vmware.com>

Author: tcdowney

lib/cloud_controller/opi/apps_client.rb

@@ -112,8 +112,8 @@ def initialize(process)
       end
 
       def to_hash
-        command = if @process.command.presence
-                    ['/bin/sh', '-c', "#{CNB_LAUNCHER_PATH} #{@process.command}"]
+        command = if @process.started_command.presence
+                    ['/bin/sh', '-c', "#{CNB_LAUNCHER_PATH} #{@process.started_command}"]
                   else
                     []
                   end

spec/unit/lib/cloud_controller/opi/apps_client_spec.rb

@@ -385,20 +385,60 @@
 
       context 'when droplet has a kpack lifecycle' do
         let(:lifecycle_type) { :kpack }
-        it 'sends a PUT request' do
-          response = client.desire_app(lrp)
 
-          expect(response.status_code).to equal(201)
-          expect(WebMock).to have_requested(:put, "#{opi_url}/apps/process-guid-#{lrp.version}").with { |request|
-            actual_body = MultiJson.load(request.body, symbolize_keys: true)
-            expected_body_with_lifecycle = expected_body.merge(lifecycle: {
-              docker_lifecycle: {
-                image: 'http://example.org/image1234',
-                command: ['/bin/sh', '-c', '/cnb/lifecycle/launcher ls -la']
-              }
-            })
-            actual_body == expected_body_with_lifecycle
-          }
+        context 'when the process has a specified start command' do
+          it 'sends a PUT request with the specified command' do
+            response = client.desire_app(lrp)
+
+            expect(response.status_code).to equal(201)
+            expect(WebMock).to have_requested(:put, "#{opi_url}/apps/process-guid-#{lrp.version}").with { |request|
+              actual_body = MultiJson.load(request.body, symbolize_keys: true)
+              expected_body_with_lifecycle = expected_body.merge(lifecycle: {
+                docker_lifecycle: {
+                  image: 'http://example.org/image1234',
+                  command: ['/bin/sh', '-c', '/cnb/lifecycle/launcher ls -la']
+                }
+              })
+              actual_body == expected_body_with_lifecycle
+            }
+          end
+        end
+
+        context 'when the process has a detected start command' do
+          let(:lrp) do
+            lrp = ::VCAP::CloudController::ProcessModel.make(:process,
+              app:                  app_model,
+              state:                'STARTED',
+              diego:                false,
+              guid:                 'process-guid',
+              type:                 'web',
+              health_check_timeout: 12,
+              instances:            21,
+              memory:               128,
+              disk_quota:           256,
+              file_descriptors:     32,
+              health_check_type:    'port',
+              enable_ssh:           false,
+            )
+            lrp.this.update(updated_at: Time.at(2))
+            lrp.reload
+          end
+
+          it 'sends a PUT request with the detected command' do
+            response = client.desire_app(lrp)
+
+            expect(response.status_code).to equal(201)
+            expect(WebMock).to have_requested(:put, "#{opi_url}/apps/process-guid-#{lrp.version}").with { |request|
+              actual_body = MultiJson.load(request.body, symbolize_keys: true)
+              expected_body_with_lifecycle = expected_body.merge(lifecycle: {
+                docker_lifecycle: {
+                  image: 'http://example.org/image1234',
+                  command: ['/bin/sh', '-c', '/cnb/lifecycle/launcher $HOME/boot.sh']
+                }
+              })
+              actual_body == expected_body_with_lifecycle
+            }
+          end
         end
       end
     end