### Question:
Ducc implements UniqueColumnCombinationsAlgorithm, RelationalInputParameterAlgorithm,
                             BooleanParameterAlgorithm { @Override public ArrayList<ConfigurationRequirement<?>> getConfigurationRequirements() { ArrayList<ConfigurationRequirement<?>> spec = new ArrayList<>(); ConfigurationRequirementRelationalInput input = new ConfigurationRequirementRelationalInput(INPUT_HANDLE); spec.add(input); ConfigurationRequirementBoolean nullEqualsNull = new ConfigurationRequirementBoolean(NULL_EQUALS_NULL); Boolean[] defaultNullEqualsNull = new Boolean[1]; defaultNullEqualsNull[0] = true; nullEqualsNull.setDefaultValues(defaultNullEqualsNull); nullEqualsNull.setRequired(true); spec.add(nullEqualsNull); return spec; } Ducc(); @Override ArrayList<ConfigurationRequirement<?>> getConfigurationRequirements(); @Override void setRelationalInputConfigurationValue(String identifier, RelationalInputGenerator... values); @Override void execute(); @Override void setResultReceiver(UniqueColumnCombinationResultReceiver receiver); @Override void setBooleanConfigurationValue(String identifier, Boolean... values); @Override String getAuthors(); @Override String getDescription();  }### Answer:
@Test public void testGetConfigurationRequirements() { ConfigurationRequirementRelationalInput expectedSpecification1 = new ConfigurationRequirementRelationalInput(Ducc.INPUT_HANDLE); ConfigurationRequirementBoolean expectedSpecification2 = new ConfigurationRequirementBoolean(Ducc.NULL_EQUALS_NULL); List<ConfigurationRequirement<?>> spec = ducc.getConfigurationRequirements(); assertEquals(2, spec.size()); assertEquals(expectedSpecification1.getIdentifier(), spec.get(0).getIdentifier()); assertEquals(expectedSpecification2.getIdentifier(), spec.get(1).getIdentifier()); }