code: public JBBPDslBuilder StructArray(final String name, final String sizeExpression) {
      final Item item = new Item(BinType.STRUCT_ARRAY, name, this.byteOrder);
      item.sizeExpression = assertExpressionChars(sizeExpression);
      this.addItem(item);
      this.openedStructCounter++;
      return this;
    }
docs: Create named structure array which size calculated by expression.
  
  @param name           name of the structure array, can be null for anonymous one
  @param sizeExpression expression to calculate array length, must not be null.
  @return the builder instance, must not be null