SSDM-55: fixed properties initialization, cleaned up unused imports

api-openbis-java/source/java/ch/ethz/sis/openbis/generic/asapi/v3/dto/common/entity/AbstractEntityPropertyHolder.java

@@ -36,7 +36,7 @@ public abstract class AbstractEntityPropertyHolder implements Serializable, IPro
 {
     @JsonProperty
     @JsonDeserialize(contentUsing = PropertiesDeserializer.class)
-    protected Map<String, Serializable> properties;
+    protected Map<String, Serializable> properties = new HashMap<>();
 
     @JsonIgnore
     public abstract Map<String, Serializable> getProperties();

api-openbis-java/source/java/ch/ethz/sis/openbis/generic/asapi/v3/dto/sample/create/SampleCreation.java

@@ -15,15 +15,9 @@
  */
 package ch.ethz.sis.openbis.generic.asapi.v3.dto.sample.create;
 
-import java.io.Serializable;
-import java.time.ZonedDateTime;
-import java.time.format.DateTimeFormatter;
 import java.util.*;
 
 import ch.ethz.sis.openbis.generic.asapi.v3.dto.common.entity.AbstractEntityCreation;
-import ch.ethz.sis.openbis.generic.asapi.v3.dto.common.id.ObjectPermId;
-import ch.ethz.sis.openbis.generic.asapi.v3.dto.common.property.PropertiesDeserializer;
-import ch.ethz.sis.openbis.generic.asapi.v3.dto.sample.id.SamplePermId;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;