code: public final void setStaticSourceFileFrom(Node other) {
      // Make sure source file prop nodes are not duplicated.
      if (other.propListHead != null
          && (this.propListHead == null
              || (this.propListHead.propType == Prop.SOURCE_FILE.ordinal()
                 && this.propListHead.next == null))) {
        // Either the node has only Prop.SOURCE_FILE as a property or has not properties.
        PropListItem tail = other.propListHead;
        while (tail.next != null) {
          tail = tail.next;
        }
        if (tail.propType == Prop.SOURCE_FILE.ordinal()) {
          propListHead = tail;
          return;
        }
      }
      setStaticSourceFile(other.getStaticSourceFile());
    }
docs: Source position management