presto-main/src/main/java/io/prestosql/execution/buffer/BufferState.java/BufferState/BufferState
class BufferState:    BufferState(boolean newPagesAllowed, boolean newBuffersAllowed, boolean terminal)
    {
        this.newPagesAllowed = newPagesAllowed;
        this.newBuffersAllowed = newBuffersAllowed;
        this.terminal = terminal;
    }