How to use

compact

method

in

org.apache.sis.internal.util.CollectionsExt

/**
 * Constructs a factory with the given default properties.
 * {@code GeodeticObjectFactory} will fallback on the map given to this constructor for any property
 * not present in the map provided to a {@code createFoo(Map<String,?>, …)} method.
 *
 * @param  properties  the default properties, or {@code null} if none.
 */
public GeodeticObjectFactory(Map<String,?> properties) {
  if (properties == null || properties.isEmpty()) {
    properties = Collections.emptyMap();
  } else {
    properties = CollectionsExt.compact(new HashMap<>(properties));
  }
  defaultProperties = properties;
  pool = new WeakHashSet<>(AbstractIdentifiedObject.class);
  parser = new AtomicReference<>();
}

/**
 * Constructs a factory with the given default properties.
 * {@code GeodeticObjectFactory} will fallback on the map given to this constructor for any property
 * not present in the map provided to a {@code createFoo(Map<String,?>, …)} method.
 *
 * @param  properties  the default properties, or {@code null} if none.
 */
public GeodeticObjectFactory(Map<String,?> properties) {
  if (properties == null || properties.isEmpty()) {
    properties = Collections.emptyMap();
  } else {
    properties = CollectionsExt.compact(new HashMap<>(properties));
  }
  defaultProperties = properties;
  pool = new WeakHashSet<>(AbstractIdentifiedObject.class);
  parser = new AtomicReference<>();
}

/**
 * Creates a new {@literal Proj.4} factory. The {@code properties} argument is an optional map
 * for specifying common properties shared by the objects to create. Some available properties are
 * {@linkplain org.apache.sis.referencing.AbstractIdentifiedObject#AbstractIdentifiedObject(Map) listed there}.
 * Unknown properties, or properties that do not apply, or properties for which {@code Proj4Factory} supplies
 * itself a value, are ignored.
 *
 * @param properties  common properties for the objects to create, or {@code null} if none.
 */
public Proj4Factory(Map<String,?> properties) {
  properties   = new HashMap(properties != null ? properties : Collections.emptyMap());
  crsFactory   = factory(CRSFactory.class,           properties, ReferencingServices.CRS_FACTORY);
  csFactory    = factory(CSFactory.class,            properties, ReferencingServices.CS_FACTORY);
  datumFactory = factory(DatumFactory.class,         properties, ReferencingServices.DATUM_FACTORY);
  mtFactory    = factory(MathTransformFactory.class, properties, ReferencingServices.MT_FACTORY);
  defaultProperties = CollectionsExt.compact(properties);
}

/**
 * Creates a new {@literal Proj.4} factory. The {@code properties} argument is an optional map
 * for specifying common properties shared by the objects to create. Some available properties are
 * {@linkplain org.apache.sis.referencing.AbstractIdentifiedObject#AbstractIdentifiedObject(Map) listed there}.
 * Unknown properties, or properties that do not apply, or properties for which {@code Proj4Factory} supplies
 * itself a value, are ignored.
 *
 * @param properties  common properties for the objects to create, or {@code null} if none.
 */
public Proj4Factory(Map<String,?> properties) {
  properties   = new HashMap<>(properties != null ? properties : Collections.emptyMap());
  crsFactory   = factory(CRSFactory.class,           properties, ReferencingServices.CRS_FACTORY);
  csFactory    = factory(CSFactory.class,            properties, ReferencingServices.CS_FACTORY);
  datumFactory = factory(DatumFactory.class,         properties, ReferencingServices.DATUM_FACTORY);
  mtFactory    = factory(MathTransformFactory.class, properties, ReferencingServices.MT_FACTORY);
  defaultProperties = CollectionsExt.compact(properties);
}

properties = CollectionsExt.compact(properties);

properties = CollectionsExt.compact(properties);

this.indices = CollectionsExt.compact(indices);

m.replaceAll((k, v) -> CollectionsExt.compact(v));
return m;

this.indices = CollectionsExt.compact(indices);

columns = CollectionsExt.compact(m);

byName       = CollectionsExt.compact(byName);
indices      = CollectionsExt.compact(indices);
assignableTo = CollectionsExt.unmodifiableOrCopy(assignableTo);

byName       = CollectionsExt.compact(byName);
indices      = CollectionsExt.compact(indices);
assignableTo = CollectionsExt.unmodifiableOrCopy(assignableTo);