addressing copilot comments

Author: ibrandes

sdk/storage/azure-storage-common/src/main/java/com/azure/storage/common/implementation/structuredmessage/StructuredMessageEncoder.java

@@ -121,27 +121,25 @@ private byte[] generateSegmentHeader(int segmentContentSize) {
      *
      * @param unencodedBuffer The buffer to be encoded.
      * @return A Flux of encoded ByteBuffers.
-     * @throws IllegalArgumentException If the buffer length exceeds the content length, or the content has already been
-     * encoded.
      */
     public Flux<ByteBuffer> encode(ByteBuffer unencodedBuffer) {
         StorageImplUtils.assertNotNull("unencodedBuffer", unencodedBuffer);
 
-        if (currentContentOffset == contentLength) {
-            return Flux
-                .error(LOGGER.logExceptionAsError(new IllegalArgumentException("Content has already been encoded.")));
-        }
+        return Flux.defer(() -> {
+            if (currentContentOffset == contentLength) {
+                return Flux.error(
+                    LOGGER.logExceptionAsError(new IllegalArgumentException("Content has already been encoded.")));
+            }
 
-        if ((unencodedBuffer.remaining() + currentContentOffset) > contentLength) {
-            return Flux.error(
-                LOGGER.logExceptionAsError(new IllegalArgumentException("Buffer length exceeds content length.")));
-        }
+            if ((unencodedBuffer.remaining() + currentContentOffset) > contentLength) {
+                return Flux.error(
+                    LOGGER.logExceptionAsError(new IllegalArgumentException("Buffer length exceeds content length.")));
+            }
 
-        if (!unencodedBuffer.hasRemaining()) {
-            return Flux.empty();
-        }
+            if (!unencodedBuffer.hasRemaining()) {
+                return Flux.empty();
+            }
 
-        return Flux.defer(() -> {
             List<ByteBuffer> buffers = new ArrayList<>();
 
             // if we are at the beginning of the message, encode message header

sdk/storage/azure-storage-common/src/test/java/com/azure/storage/common/implementation/structuredmessage/MessageEncoderTests.java

@@ -9,6 +9,7 @@
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
+import reactor.test.StepVerifier;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -24,6 +25,7 @@
 import static com.azure.storage.common.implementation.structuredmessage.StructuredMessageConstants.V1_HEADER_LENGTH;
 import static com.azure.storage.common.implementation.structuredmessage.StructuredMessageConstants.V1_SEGMENT_HEADER_LENGTH;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
 public class MessageEncoderTests {
@@ -215,16 +217,18 @@ public void emptyBuffer() {
     public void contentAlreadyEncoded() {
         StructuredMessageEncoder encoder = new StructuredMessageEncoder(4, 2, StructuredMessageFlags.NONE);
         encoder.encode(ByteBuffer.wrap(new byte[] { 1, 2, 3, 4 })).blockLast();
-        assertThrows(IllegalArgumentException.class,
-            () -> encoder.encode(ByteBuffer.wrap(new byte[] { 1, 2 })).blockLast());
+        StepVerifier.create(encoder.encode(ByteBuffer.wrap(new byte[] { 1, 2 })))
+            .expectError(IllegalArgumentException.class)
+            .verify();
     }
 
     @Test
     public void bufferLengthExceedsContentLength() {
         StructuredMessageEncoder encoder = new StructuredMessageEncoder(4, 2, StructuredMessageFlags.NONE);
         encoder.encode(ByteBuffer.wrap(new byte[] { 1, 2, 3 })).blockLast();
-        assertThrows(IllegalArgumentException.class,
-            () -> encoder.encode(ByteBuffer.wrap(new byte[] { 1, 2 })).blockLast());
+        StepVerifier.create(encoder.encode(ByteBuffer.wrap(new byte[] { 1, 2 })))
+            .expectError(IllegalArgumentException.class)
+            .verify();
     }
 
     @Test