[#23] Update proto api

Add chain functionality
Add tests
Signed-off-by: Ori Bruk <o.bruk@yadro.com>

cryptography/src/main/java/info/frostfs/sdk/Helper.java

@@ -3,6 +3,7 @@ package info.frostfs.sdk;
 import com.google.protobuf.ByteString;
 import com.google.protobuf.Message;
 import info.frostfs.sdk.exceptions.ValidationFrostFSException;
+import org.apache.commons.lang3.StringUtils;
 import org.bouncycastle.crypto.digests.RIPEMD160Digest;
 
 import java.math.BigInteger;
@@ -15,6 +16,7 @@ import static java.util.Objects.isNull;
 public class Helper {
     private static final String SHA256 = "SHA-256";
     private static final int RIPEMD_160_HASH_BYTE_LENGTH = 20;
+    private static final int HEX_RADIX = 16;
 
     private Helper() {
     }
@@ -62,4 +64,12 @@ public class Helper {
 
         return String.format("%0" + (value.length << 1) + "x", new BigInteger(1, value));
     }
+
+    public static byte[] getByteArrayFromHex(String hex) {
+        if (StringUtils.isBlank(hex)) {
+            throw new ValidationFrostFSException(INPUT_PARAM_IS_MISSING);
+        }
+
+        return new BigInteger(hex, HEX_RADIX).toByteArray();
+    }
 }

cryptography/src/test/java/info/frostfs/sdk/HelperTest.java

@@ -108,4 +108,23 @@ public class HelperTest {
         assertThrows(ValidationFrostFSException.class, () -> Helper.getHexString(null));
         assertThrows(ValidationFrostFSException.class, () -> Helper.getHexString(new byte[]{}));
     }
+
+    @Test
+    void getByteArrayFromHex_success() {
+        //Given
+        var value = "0102030405";
+
+        //When
+        var result = Helper.getByteArrayFromHex(value);
+
+        //Then
+        assertThat(result).containsOnly(new byte[]{1, 2, 3, 4, 5});
+    }
+
+    @Test
+    void getByteArrayFromHex_wrong() {
+        //When + Then
+        assertThrows(ValidationFrostFSException.class, () -> Helper.getByteArrayFromHex(null));
+        assertThrows(ValidationFrostFSException.class, () -> Helper.getByteArrayFromHex(""));
+    }
 }