Add missing spaces.

Of course one might ask if we should consider using text blocks here :) Then:

- We might put the whole description on one very long line.
- We might wrap around 100 columns and escape the newlines.
- We might use _unescaped_ newlines but configure Error Prone to replace all newlines with spaces internally. (We could in theory even give google-java-format special knowledge of `@BugPattern` so that it could wrap automatically.)

(And in all that, we have the option to outdent the text block or not.)

PiperOrigin-RevId: 697993965

core/src/main/java/com/google/errorprone/bugpatterns/UnsafeReflectiveConstructionCast.java

@@ -46,8 +46,8 @@
     summary =
         "Prefer `asSubclass` instead of casting the result of `newInstance`,"
             + " to detect classes of incorrect type before invoking their constructors."
-            + "This way, if the class is of the incorrect type,"
-            + "it will throw an exception before invoking its constructor.",
+            + " This way, if the class is of the incorrect type,"
+            + " it will throw an exception before invoking its constructor.",
     severity = WARNING,
     tags = StandardTags.FRAGILE_CODE)
 public class UnsafeReflectiveConstructionCast extends BugChecker implements TypeCastTreeMatcher {