HADOOP-18975. FIPs. only set the option once, but always do it

Change-Id: I62157b716c0b93ee6684064fae70f89aac10b8d5

Author: steveloughran

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/DefaultS3ClientFactory.java

@@ -175,8 +175,6 @@ private <BuilderT extends S3BaseClientBuilder<BuilderT, ClientT>, ClientT> Build
             .pathStyleAccessEnabled(parameters.isPathStyleAccess())
             .build();
 
-    builder.fipsEnabled(parameters.isFipsEnabled());
-
     return builder
         .overrideConfiguration(createClientOverrideConfiguration(parameters, conf))
         .credentialsProvider(parameters.getCredentialSet())
@@ -260,12 +258,14 @@ private <BuilderT extends S3BaseClientBuilder<BuilderT, ClientT>, ClientT> void
       region = Region.of(configuredRegion);
     }
 
-    // FIPs? Set it, then reject any attempt to set an endpoint
+    // FIPs? Log it, then reject any attempt to set an endpoint
     final boolean fipsEnabled = parameters.isFipsEnabled();
     if (fipsEnabled) {
       LOG.debug("Enabling FIPS mode");
-      builder.fipsEnabled(true);
     }
+    // always setting it guarantees the value is non-null,
+    // which tests expect.
+    builder.fipsEnabled(fipsEnabled);
 
     if (endpoint != null) {
       checkArgument(!fipsEnabled,

hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/ITestS3AEndpointRegion.java

@@ -293,7 +293,9 @@ public void beforeExecution(Context.BeforeExecution context,
       // verify the fips state matches expectation.
       Assertions.assertThat(executionAttributes.getAttribute(
           AwsExecutionAttribute.FIPS_ENDPOINT_ENABLED))
-          .describedAs("Incorrect FIPS flag set").isEqualTo(isFips);
+          .describedAs("Incorrect FIPS flag set in execution attributes")
+          .isNotNull()
+          .isEqualTo(isFips);
 
       // We don't actually want to make a request, so exit early.
       throw AwsServiceException.builder().message(EXCEPTION_THROWN_BY_INTERCEPTOR).build();
@@ -309,6 +311,7 @@ public void beforeExecution(Context.BeforeExecution context,
    * @param expectedRegion the region that should be set in the client.
    * @param isFips is this a FIPS endpoint?
    * @return the client.
+   * @throws IOException IO problems
    */
   @SuppressWarnings("deprecation")
   private S3Client createS3Client(Configuration conf,