### Question:
GroupBlock implements ContainerBlock { @Override public String toString() { StringBuilder builder = new StringBuilder(); builder.append("{ "); for (Block block : blocks) { builder.append(block.toString()).append(" "); } if (filters != null) { builder.append(" FILTER(").append(filters).append(")"); } builder.append(" }"); return builder.toString(); } GroupBlock(List<Block> blocks, Predicate... filters); @Override Predicate not(); @Override @SuppressWarnings("unchecked") R accept(Visitor<R, C> v, C context); @Override Class<? extends Boolean> getType(); List<Block> getBlocks(); @Nullable Predicate getFilters(); @Override BooleanExpression exists(); @Override int hashCode(); @Override boolean equals(Object o); @Override String toString();  }### Answer:
@Test public void To_String() { Block block = Blocks.group(Blocks.S_FIRST, Blocks.S_REST); assertEquals( "{ {s} http: "{s} http: block.toString()); }