code refactor

sdk/identity/azure-identity/src/main/java/com/azure/identity/implementation/IdentityClient.java

@@ -480,39 +480,12 @@ private Mono<AccessToken> getAccessTokenFromPowerShell(TokenRequestContext reque
                     Map<String, String> objectMap = reader.readMap(JsonReader::getString);
                     String accessToken = objectMap.get("Token");
                     String time = objectMap.get("ExpiresOn");
-                    OffsetDateTime expiresInstant = null;
-
-                    if (!CoreUtils.isNullOrEmpty(time)) {
-                        try {
-                            expiresInstant = OffsetDateTime.parse(time).withOffsetSameInstant(ZoneOffset.UTC);
-                        } catch (DateTimeParseException ex) {
-
-                            final String prefix = "/Date(";
-                            final String suffix = ")/";
-                            if (time.length() > prefix.length() + suffix.length()
-                                && time.startsWith(prefix)
-                                && time.endsWith(suffix)) {
-                                String digits = time.substring(prefix.length(), time.length() - suffix.length());
-                                boolean allDigits = true;
-                                for (int i = 0; i < digits.length(); i++) {
-                                    if (!Character.isDigit(digits.charAt(i))) {
-                                        allDigits = false;
-                                        break;
-                                    }
-                                }
-                                if (allDigits) {
-                                    try {
-                                        long epochMs = Long.parseLong(digits);
-                                        expiresInstant
-                                            = OffsetDateTime.ofInstant(Instant.ofEpochMilli(epochMs), ZoneOffset.UTC);
-                                    } catch (NumberFormatException ignore) {
-                                        // leave expiresInstant null -> handled downstream
-                                    }
-                                }
-                            }
-                        }
+                    OffsetDateTime expiresOn = PowerShellUtil.parseExpiresOn(time);
+                    if (expiresOn == null) {
+                        return Mono.error(LoggingUtil.logCredentialUnavailableException(LOGGER, options,
+                            new CredentialUnavailableException("Encountered error when deserializing ExpiresOn time from PowerShell response.")));
                     }
-                    return Mono.just(new AccessToken(accessToken, expiresInstant));
+                    return Mono.just(new AccessToken(accessToken, expiresOn));
                 } catch (IOException e) {
                     return Mono.error(LoggingUtil.logCredentialUnavailableException(LOGGER, options,
                         new CredentialUnavailableException(

sdk/identity/azure-identity/src/main/java/com/azure/identity/implementation/util/PowerShellUtil.java

@@ -3,6 +3,13 @@
 
 package com.azure.identity.implementation.util;
 
+import java.time.Instant;
+import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
+import java.time.format.DateTimeParseException;
+
+import com.azure.core.util.CoreUtils;
+
 /**
  * Utility class for powershell auth related ops .
  */
@@ -48,4 +55,42 @@ public static String getPwshCommand(String tenantId, String scope, String sep) {
             + "}" + sep
             + "$customToken | ConvertTo-Json -Compress";
     }
+
+    /**
+     * Parse ExpiresOn returned from PowerShell. Supports ISO timestamps and the .NET "/Date(<ms>)/" form.
+     *
+     * @param time the string value returned by PowerShell
+     * @return parsed OffsetDateTime in UTC or null if unable to parse
+     */
+    public static OffsetDateTime parseExpiresOn(String time) {
+        if (CoreUtils.isNullOrEmpty(time)) {
+            return null;
+        }
+
+        // Try ISO first
+        try {
+            return OffsetDateTime.parse(time).withOffsetSameInstant(ZoneOffset.UTC);
+        } catch (DateTimeParseException ignore) {
+            // fall through to .NET style parsing
+        }
+
+        final String prefix = "/Date(";
+        final String suffix = ")/";
+        if (time.length() > prefix.length() + suffix.length()
+            && time.startsWith(prefix) && time.endsWith(suffix)) {
+            String digits = time.substring(prefix.length(), time.length() - suffix.length());
+            for (int i = 0; i < digits.length(); i++) {
+                if (!Character.isDigit(digits.charAt(i))) {
+                    return null;
+                }
+            }
+            try {
+                long epochMs = Long.parseLong(digits);
+                return OffsetDateTime.ofInstant(Instant.ofEpochMilli(epochMs), ZoneOffset.UTC);
+            } catch (NumberFormatException ignore) {
+                return null;
+            }
+        }
+        return null;
+    }
 }