public void set(
      int n,
      int startPc,
      int length,
      CstString name,
      CstString descriptor,
      CstString signature,
      int index) {
    set0(n, new Item(startPc, length, name, descriptor, signature, index));
  }
Sets the item at the given index.

<p><b>Note:</b> At least one of {@code descriptor} or {@code signature} must be passed as
non-null.

@param n {@code >= 0, < size();} which element
@param startPc {@code >= 0;} the start pc of this variable's scope
@param length {@code >= 0;} the length (in bytecodes) of this variable's scope
@param name {@code non-null;} the variable's name
@param descriptor {@code null-ok;} the variable's type descriptor
@param signature {@code null-ok;} the variable's type signature
@param index {@code >= 0;} the variable's local index
android/android_framework/dex-maker/src/main/java/com/android/dx/cf/code/LocalVariableList.java