diff --git a/core/src/main/java/com/google/adk/sessions/State.java b/core/src/main/java/com/google/adk/sessions/State.java
index 70d2dfbf2..ec23857d9 100644
--- a/core/src/main/java/com/google/adk/sessions/State.java
+++ b/core/src/main/java/com/google/adk/sessions/State.java
@@ -24,7 +24,6 @@
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
-import javax.annotation.Nullable;
 
 /** A {@link State} object that also keeps track of the changes to the state. */
 @SuppressWarnings("ShouldNotSubclass")
@@ -40,22 +39,13 @@ public final class State implements ConcurrentMap<String, Object> {
   private final ConcurrentMap<String, Object> state;
   private final ConcurrentMap<String, Object> delta;
 
-  public State(Map<String, Object> state) {
-    this(state, null);
-  }
-
-  public State(Map<String, Object> state, @Nullable Map<String, Object> delta) {
-    Objects.requireNonNull(state, "state is null");
-    this.state =
-        state instanceof ConcurrentMap
-            ? (ConcurrentMap<String, Object>) state
-            : new ConcurrentHashMap<>(state);
-    this.delta =
-        delta == null
-            ? new ConcurrentHashMap<>()
-            : delta instanceof ConcurrentMap
-                ? (ConcurrentMap<String, Object>) delta
-                : new ConcurrentHashMap<>(delta);
+  public State(ConcurrentMap<String, Object> state) {
+    this(state, new ConcurrentHashMap<>());
+  }
+
+  public State(ConcurrentMap<String, Object> state, ConcurrentMap<String, Object> delta) {
+    this.state = Objects.requireNonNull(state);
+    this.delta = delta;
   }
 
   @Override
diff --git a/core/src/test/java/com/google/adk/sessions/StateTest.java b/core/src/test/java/com/google/adk/sessions/StateTest.java
deleted file mode 100644
index e1fcaeadc..000000000
--- a/core/src/test/java/com/google/adk/sessions/StateTest.java
+++ /dev/null
@@ -1,50 +0,0 @@
-package com.google.adk.sessions;
-
-import static com.google.common.truth.Truth.assertThat;
-
-import java.util.HashMap;
-import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.ConcurrentMap;
-import org.junit.Assert;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.JUnit4;
-
-@RunWith(JUnit4.class)
-public class StateTest {
-  @Test
-  public void constructor_nullDelta_createsEmptyConcurrentHashMap() {
-    ConcurrentMap<String, Object> stateMap = new ConcurrentHashMap<>();
-    State state = new State(stateMap, null);
-    assertThat(state.hasDelta()).isFalse();
-    state.put("key", "value");
-    assertThat(state.hasDelta()).isTrue();
-  }
-
-  @Test
-  public void constructor_nullState_throwsException() {
-    Assert.assertThrows(NullPointerException.class, () -> new State(null, new HashMap<>()));
-  }
-
-  @Test
-  public void constructor_regularMapState() {
-    Map<String, Object> stateMap = new HashMap<>();
-    stateMap.put("initial", "val");
-    State state = new State(stateMap, null);
-    // It should have copied the contents
-    assertThat(state).containsEntry("initial", "val");
-    state.put("key", "value");
-    // The original map should NOT be updated because a copy was created
-    assertThat(stateMap).doesNotContainKey("key");
-  }
-
-  @Test
-  public void constructor_singleArgument() {
-    ConcurrentMap<String, Object> stateMap = new ConcurrentHashMap<>();
-    State state = new State(stateMap);
-    assertThat(state.hasDelta()).isFalse();
-    state.put("key", "value");
-    assertThat(state.hasDelta()).isTrue();
-  }
-}