#Java 8, 131 bytes

<!-- language-all: lang-java -->

    import java.util.*;a->{Set r=new HashSet();for(String s:a)if("import jav.ul*;->{Se=nwHsh()fg:\"cd}".contains(s))r.add(s);return r;}

**Explanation:**

[Try it here.](https://tio.run/##lZNNTxRBEIbv@yvKVXQG2cEv/GAANX5xETQcPLC46Z2p3Wno6dl097CuuAnKwYSDJw4mYoIJ3jhpYkLQC3hQf4UsMf4MfBchmhgPm/T0THf1W/VUT9WsmBelrMF6Np7bl2kjM45msRfkTqqgPySiwUG6J7Cd1cglTNWW41KU5doVCpES1tJdIfVCgUhqx6YmIqaJ7pJoit3IjUQYEcEwRpE35YzU9ekZEn6IE@0CJuuEkxFNkKZR2helsQXIyIxqbtK4sAlWnh/WMnOoJjssfFnzin9og1z1hwfCUd0ct4nn1@rD5WIUt4tBlGkHPutZ3zeBiGN8hIZdbjSZsL3f5cBo5FUFikOY@UzGlEL2N/FhTi3rOA2y3AUNmJzSng4ir3hdVRk0txDKsdTFwDaUdF6x6PsHuf5fWS5XKh5NViqTfmWwB92xa8dP9D082e/5ldML7SdIeGTsag/6s@fOXxi6eOnylTOl0emZcjk8NRD0Et/bW3rx/d3az1fLmH0sfnx601nZ6qw8xdyDn87i6vb6WN9Atru1/GX92xrWOy93t95@Xh66uf1@d3Npd3Pt68f721uz4c7zENawvf2hs/i6lxArG52VxYOxQSD1aO/ZagkPvv0e/NwWhrCJSj9ohVxHqG7HMVVFNNcUqHJ71Ca5rqF4ZaZFVTGxjo8MDxi@UXxTDWmEImHSI8sdocSjFinJlgTZVCgFN4brwsSI0WKlsibZXAc0aarSdZvBJRKHHc7HEsWr0XzwZrK8nqgWaanZtUos64mjVCoFnu4bAboyTbkDCw6iamVdy5qMhHYgcA7QVZVzqW6YNTWUgCdqJpllEg0uxWwjJAUsJWtMaM8UDg2TzUik4jHY4BaXl4JznsEJSCTZQouBo8ut58Bclw6XgKuLEv7tQEDFzgGeIZExi@CfP9QutPd/AQ)

    import java.util.*;     // Required import for Set and HashSet
    
    a->{                    // Method with String-array parameter and Set return-type
      Set r=new HashSet();  //  The result Set
      for(String s:a)       //  Loop over the input String-array
        if("import jav.ul*;->{Se=nwHsh()fg:\"cd}".contains(s))
                            //   If the current character is part of the source-code:
          r.add(s);         //    Add it to the Set
                            //  End of loop (implicit / single-line body)
      return r;             //  Return the result-Set
    }                       // End of method