Avoid work in Optional.orElse() calls

Any code inside the orElse() will always be called, even if the result
isn't used because the optional is present. This is wasteful at a
minimum and can be actively harmful (as seen in [1]) because of side
effects or performance impacts. Fix that by replacing all orElse() calls
that create new instances or do non-constant work with a call to
orElseGet().

It would be nice if there were an ErrorProne checker for this, but one
doesn't exist yet.

[1] https://gerrit-review.googlesource.com/c/gerrit/+/417915/comment/0ea287cd_bfecb7f2/

Release-Notes: skip
Change-Id: I2d3d59da88cd04a2e589b7255fc0877719a57432

src/main/java/com/googlesource/gerrit/plugins/manager/repository/CorePluginsRepository.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/manager/repository/CorePluginsRepository.java b/src/main/java/com/googlesource/gerrit/plugins/manager/repository/CorePluginsRepository.java
index 21e2a8d..2e175ea 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/manager/repository/CorePluginsRepository.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/manager/repository/CorePluginsRepository.java
@@ -77,13 +77,14 @@
                       "",
                       pluginUrl.toString());
                 })
-            .orElse(
-                new PluginInfo(
-                    dropSuffix(entryName.getFileName().toString(), ".jar"),
-                    "",
-                    "",
-                    "",
-                    pluginUrl.toString()));
+            .orElseGet(
+                () ->
+                    new PluginInfo(
+                        dropSuffix(entryName.getFileName().toString(), ".jar"),
+                        "",
+                        "",
+                        "",
+                        pluginUrl.toString()));
       } catch (IOException e) {
         logger.atSevere().withCause(e).log("Unable to open plugin %s", pluginUrl);
         return null;

src/main/java/com/googlesource/gerrit/plugins/manager/repository/JenkinsCiPluginsRepository.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/manager/repository/JenkinsCiPluginsRepository.java b/src/main/java/com/googlesource/gerrit/plugins/manager/repository/JenkinsCiPluginsRepository.java
index 2260a65..76254a6 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/manager/repository/JenkinsCiPluginsRepository.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/manager/repository/JenkinsCiPluginsRepository.java
@@ -119,7 +119,7 @@
     Optional<SmartJson> buildExecution = tryGetJson(url + "/api/json");
     Optional<JsonArray> artifacts =
         buildExecution.map(json -> json.get("artifacts").get().getAsJsonArray());
-    if (artifacts.orElse(new JsonArray()).size() == 0) {
+    if (artifacts.orElseGet(() -> new JsonArray()).size() == 0) {
       return Optional.empty();
     }