Fix: don't inline level prefix if breaks occurred inside

changelog/@unreleased/pr-85.v2.yml

@@ -0,0 +1,6 @@
+type: fix
+fix:
+  description: "When inlining a level's leading docs, check that no breaks were introduced
+    more robustly."
+  links:
+  - https://github.com/palantir/palantir-java-format/pull/85

palantir-java-format/src/main/java/com/palantir/javaformat/doc/Level.java

@@ -295,8 +295,11 @@ private Optional<State> tryBreakLastLevel(
         SplitsBreaks prefixSplitsBreaks = splitByBreaks(leadingDocs);
 
         State state1 = tryToLayOutLevelOnOneLine(commentsHelper, maxWidth, state, prefixSplitsBreaks, explorationNode);
-        Preconditions.checkState(
-                !state1.mustBreak(), "We messed up, it wants to break a bunch of splits that shouldn't be broken");
+        // If a break was still forced somehow even though we could fit the leadingWidth, then abort.
+        // This could happen if inner levels have set a `columnLimitBeforeLastBreak` or something like that.
+        if (state1.numLines() != state.numLines()) {
+            return Optional.empty();
+        }
 
         // Ok now how to handle the last level?
         // There are two options:

palantir-java-format/src/test/resources/com/palantir/javaformat/java/testdata/palantir-conjure-java-runtime-1285-1.output

@@ -8,8 +8,10 @@ class PalantirConjureJavaRuntime1285_SslSocketFactories {
         KeyManager[] keyManagers = null;
         if (config.keyStorePath().isPresent()) {
             keyManagers = createKeyManagerFactory(
-                            config.keyStorePath().get(), config.keyStorePassword()
-                                    .get(), config.keyStoreType(), config.keyStoreKeyAlias())
+                            config.keyStorePath().get(),
+                            config.keyStorePassword().get(),
+                            config.keyStoreType(),
+                            config.keyStoreKeyAlias())
                     .getKeyManagers();
         }