fix: update encoding header handling in DsnGet and add corresponding test

Signed-off-by: Kasper Helsted <helsted@vopu.dk>

Author: KasperHelsted

src/main/java/zowe/client/sdk/zosfiles/dsn/methods/DsnGet.java

@@ -139,8 +139,12 @@ public InputStream get(final String targetName, final DsnDownloadInputData downl
             value = ZosmfHeaders.HEADERS.get("X_IBM_BINARY").get(1);
             headers.put(key, value);
         } else if (downloadInputData.getEncoding().isPresent()) {
-            key = ZosmfHeaders.X_IBM_TEXT;
-            value = ZosmfHeaders.X_IBM_TEXT + ZosmfHeaders.X_IBM_TEXT_ENCODING + downloadInputData.getEncoding();
+            key = ZosmfHeaders.HEADERS.get("X_IBM_TEXT").get(0);
+            value = String.format("%s%sIBM-%s",
+                    ZosmfHeaders.HEADERS.get("X_IBM_TEXT").get(1),
+                    ZosmfHeaders.HEADERS.get("X_IBM_TEXT_ENCODING").get(0),
+                    downloadInputData.getEncoding().getAsLong()
+            );
             headers.put(key, value);
         }
 

src/test/java/zowe/client/sdk/zosfiles/dsn/methods/DsnGetTest.java

@@ -106,6 +106,21 @@ public void tstDsnGetTokenWithMultipleParamsSuccess() throws ZosmfRequestExcepti
         assertEquals("https://1:443/zosmf/restfiles/ds/TEST.DATASET", mockGetRequestToken.getUrl());
     }
 
+    @Test
+    public void tstDsnGetTokenWithOnlyEncodingParamsSuccess() throws ZosmfRequestException, IOException {
+        final DsnGet dsnGet = new DsnGet(connection, mockGetRequestToken);
+        final DsnDownloadInputData downloadInputData = new DsnDownloadInputData.Builder()
+                .encoding(1047L)
+                .build();
+        final InputStream inputStream = dsnGet.get("TEST.DATASET", downloadInputData);
+        assertEquals("{X-IBM-Data-Type=text;fileEncoding=IBM-1047, " +
+                        "Accept-Encoding=1047, X-CSRF-ZOSMF-HEADER=true, " +
+                        "Content-Type=application/json}",
+                mockGetRequestToken.getHeaders().toString());
+        assertEquals("test data", new String(inputStream.readAllBytes()));
+        assertEquals("https://1:443/zosmf/restfiles/ds/TEST.DATASET", mockGetRequestToken.getUrl());
+    }
+
     @Test
     public void tstDsnGetTokenWithMultipleParamsWithoutEncodingSuccess() throws ZosmfRequestException, IOException {
         final DsnGet dsnGet = new DsnGet(connection, mockGetRequestToken);