Remove the unused ProtoCompileActionBuilder#setLangParameter().

RELNOTES: None.
PiperOrigin-RevId: 251805344
diff --git a/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoCompileActionBuilder.java b/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoCompileActionBuilder.java
index 6d5d912..1f884d8 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoCompileActionBuilder.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoCompileActionBuilder.java
@@ -69,7 +69,6 @@
   private final String langPrefix;
   private final Iterable<Artifact> outputs;
   private Iterable<Artifact> inputs;
-  private String langParameter;
   private String langPluginName;
   private Supplier<String> langPluginParameter;
   private boolean hasServices;
@@ -87,11 +86,6 @@
     return this;
   }
 
-  public ProtoCompileActionBuilder setLangParameter(String langParameter) {
-    this.langParameter = langParameter;
-    return this;
-  }
-
   public ProtoCompileActionBuilder setLangPluginName(String langPluginName) {
     this.langPluginName = langPluginName;
     return this;
@@ -279,10 +273,6 @@
       result.addLazyString(new LazyLangPluginFlag(langPrefix, langPluginParameter));
     }
 
-    if (langParameter != null) {
-      result.addDynamicString(langParameter);
-    }
-
     result.addAll(ruleContext.getFragment(ProtoConfiguration.class).protocOpts());
 
     boolean areDepsStrict = areDepsStrict(ruleContext);