### Question:
SecureKeyBlock extends SecureKey { public Map<String, String> getOptionalHeaders() { return Collections.unmodifiableMap(optionalHeaders); } protected  SecureKeyBlock(); @Override void setKeyType(String keyType); @Override String getKeyType(); @Override void setKeyLength(short keyLength); @Override short getKeyLength(); @Override KeyScheme getScheme(); char getKeyBlockVersion(); int getKeyBlockLength(); KeyUsage getKeyUsage(); Algorithm getAlgorithm(); ModeOfUse getModeOfUse(); String getKeyVersion(); Exportability getExportability(); String getReserved(); Map<String, String> getOptionalHeaders(); byte[] getKeyBlockMAC(); @Override void dump(PrintStream p, String indent);  }### Answer:
@Test public void testGetOptionalHeaders() { Map<String, String> expResult = new LinkedHashMap<>(); Map<String, String> result = instance.getOptionalHeaders(); assertEquals(expResult, result); }