code: public static boolean isP2PK(Script script) {
          List<ScriptChunk> chunks = script.chunks;
          if (chunks.size() != 2)
              return false;
          ScriptChunk chunk0 = chunks.get(0);
          if (chunk0.isOpCode())
              return false;
          byte[] chunk0data = chunk0.data;
          if (chunk0data == null)
              return false;
          if (chunk0data.length <= 1)
              return false;
          if (!chunks.get(1).equalsOpCode(OP_CHECKSIG))
              return false;
          return true;
      }
docs: Returns true if this script is of the form {@code <pubkey> OP_CHECKSIG}. This form was originally intended for transactions
  where the peers talked to each other directly via TCP/IP, but has fallen out of favor with time due to that mode
  of operation being susceptible to man-in-the-middle attacks. It is still used in coinbase outputs and can be
  useful more exotic types of transaction, but today most payments are to addresses.