code: protected ChildReferences getChildReferencesFromBlock( Document block, boolean allowsSNS ) {
          if (!block.containsField(CHILDREN)) {
              return ImmutableChildReferences.EMPTY_CHILD_REFERENCES;
          }
          return ImmutableChildReferences.create(this, block, CHILDREN, allowsSNS);
      }
docs: Reads the children of the given block and returns a {@link ChildReferences} instance.
  
  @param block a {@code non-null} {@link Document} representing a block of children
  @param allowsSNS {@code true} if the child references instance should be SNS aware, {@code false} otherwise
  @return a {@code non-null} child references instance