Fix assignment for last element in codegen list

Bug: 322973175
Test: TH
Change-Id: Ib55bea6050e0d125c0d7d4821d75101085ab48af

tools/codegen/src/com/android/codegen/FileInfo.kt

@@ -238,7 +238,7 @@ class FileInfo(
                     } else if (classBounds.isDataclass) {
 
                         // Insert placeholder for generated code to be inserted for the 1st time
-                        chunks.last = (chunks.last as Code)
+                        chunks[chunks.lastIndex] = (chunks.last() as Code)
                                 .lines
                                 .dropLastWhile { it.isBlank() }
                                 .run {
@@ -286,4 +286,4 @@ class FileInfo(
                     .let { addAll(it) }
         }
     }
-}
+}
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tools/codegen/src/com/android/codegen/Utils.kt

@@ -137,14 +137,4 @@ private fun parseFailed(source: String, cause: Throwable? = null, desc: String =
             cause)
 }
 
-var <T> MutableList<T>.last
-    get() = last()
-    set(value) {
-        if (isEmpty()) {
-            add(value)
-        } else {
-            this[size - 1] = value
-        }
-    }
-
-inline fun <T> buildList(init: MutableList<T>.() -> Unit) = mutableListOf<T>().apply(init)
+inline fun <T> buildList(init: MutableList<T>.() -> Unit) = mutableListOf<T>().apply(init)
\ No newline at end of file