Govt and cops put those dumpsters there on purpose to have voilance to paint a peaceful demonstration voilant and take action against the main people of these peaceful demos. see how nicely they destroying and someone has rightly said on youtube that
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The athletic masked people not touched by the police who are smashing everything are called Agents Provocateurs who are paid to cause violence to make the peaceful protests look bad and give police an excuse to hurt the peaceful people."