docs: public <OUT> DataStreamSource<OUT> fromCollection(Collection<OUT> data, TypeInformation<OUT> typeInfo) {
  		Preconditions.checkNotNull(data, "Collection must not be null");
  
  		// must not have null elements and mixed elements
  		FromElementsFunction.checkCollection(data, typeInfo.getTypeClass());
  
  		SourceFunction<OUT> function;
  		try {
  			function = new FromElementsFunction<>(typeInfo.createSerializer(getConfig()), data);
  		}
  		catch (IOException e) {
  			throw new RuntimeException(e.getMessage(), e);
  		}
  		return addSource(function, "Collection Source", typeInfo).setParallelism(1);
  	}