doc updates and added test coverage

Signed-off-by: Pradeep <[email protected]>

Author: pradeepbbl

Diff for: providers/flagd/README.md

@@ -112,6 +112,7 @@ Given below are the supported configurations:
 | maxEventStreamRetries | FLAGD_MAX_EVENT_STREAM_RETRIES | int                      | 5         | rpc                 |
 | retryBackoffMs        | FLAGD_RETRY_BACKOFF_MS         | int                      | 1000      | rpc                 |
 | offlineFlagSourcePath | FLAGD_OFFLINE_FLAG_SOURCE_PATH | String                   | null      | in-process          |
+| authority             | FLAGD_AUTHORITY_OVERRIDE       | String                   | null      | rpc & in-process    |
 
 > [!NOTE]  
 > Some configurations are only applicable for RPC resolver.

Diff for: providers/flagd/src/test/java/dev/openfeature/contrib/providers/flagd/FlagdOptionsTest.java

@@ -34,6 +34,7 @@ void TestDefaults() {
         assertNull(builder.getOfflineFlagSourcePath());
         assertEquals(Resolver.RPC, builder.getResolverType());
         assertEquals(0, builder.getKeepAlive());
+        assertNull(builder.getAuthority());
     }
 
     @Test
@@ -55,6 +56,7 @@ void TestBuilderOptions() {
                 .customConnector(connector)
                 .resolverType(Resolver.IN_PROCESS)
                 .keepAlive(1000)
+                .authority("test.service")
                 .build();
 
         assertEquals("https://hosted-flagd", flagdOptions.getHost());
@@ -70,6 +72,7 @@ void TestBuilderOptions() {
         assertEquals(connector, flagdOptions.getCustomConnector());
         assertEquals(Resolver.IN_PROCESS, flagdOptions.getResolverType());
         assertEquals(1000, flagdOptions.getKeepAlive());
+        assertEquals("test.service", flagdOptions.getAuthority());
     }
 
 
@@ -187,4 +190,13 @@ void testRpcProviderFromEnv_portConfigured_usesConfiguredPort() {
         assertThat(flagdOptions.getPort()).isEqualTo(1534);
 
     }
+
+
+    @Test
+    @SetEnvironmentVariable(key = AUTHORITY_OVERRIDE, value = "test.service")
+    void testAuthorityOverrideFromEnv() {
+        FlagdOptions flagdOptions = FlagdOptions.builder().build();
+
+        assertThat(flagdOptions.getAuthority()).isEqualTo("test.service");
+    }
 }