diff --git a/api/src/main/java/io/opentelemetry/api/OpenTelemetry.java b/api/src/main/java/io/opentelemetry/api/OpenTelemetry.java
index d4c61656da3..0dc9ce0a99a 100644
--- a/api/src/main/java/io/opentelemetry/api/OpenTelemetry.java
+++ b/api/src/main/java/io/opentelemetry/api/OpenTelemetry.java
@@ -12,6 +12,7 @@
 import io.opentelemetry.api.trace.Tracer;
 import io.opentelemetry.api.trace.TracerProvider;
 import io.opentelemetry.context.propagation.ContextPropagators;
+import javax.annotation.Nullable;
 
 /**
  * The entrypoint to telemetry functionality for tracing, metrics and baggage.
@@ -169,7 +170,7 @@ default Tracer getTracer(String instrumentationName) {
    *     "semver:1.0.0").
    * @return a tracer instance.
    */
-  default Tracer getTracer(String instrumentationName, String instrumentationVersion) {
+  default Tracer getTracer(String instrumentationName, @Nullable String instrumentationVersion) {
     return getGlobalTracerProvider().get(instrumentationName, instrumentationVersion);
   }
 
diff --git a/api/src/main/java/io/opentelemetry/api/metrics/DefaultMeterProvider.java b/api/src/main/java/io/opentelemetry/api/metrics/DefaultMeterProvider.java
index 4516c098dc5..b35a5a288a4 100644
--- a/api/src/main/java/io/opentelemetry/api/metrics/DefaultMeterProvider.java
+++ b/api/src/main/java/io/opentelemetry/api/metrics/DefaultMeterProvider.java
@@ -5,6 +5,7 @@
 
 package io.opentelemetry.api.metrics;
 
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 
 @ThreadSafe
@@ -22,7 +23,7 @@ public Meter get(String instrumentationName) {
   }
 
   @Override
-  public Meter get(String instrumentationName, String instrumentationVersion) {
+  public Meter get(String instrumentationName, @Nullable String instrumentationVersion) {
     return Meter.getDefault();
   }
 
diff --git a/api/src/main/java/io/opentelemetry/api/metrics/MeterProvider.java b/api/src/main/java/io/opentelemetry/api/metrics/MeterProvider.java
index ceedaca7da3..92719ecb1e2 100644
--- a/api/src/main/java/io/opentelemetry/api/metrics/MeterProvider.java
+++ b/api/src/main/java/io/opentelemetry/api/metrics/MeterProvider.java
@@ -6,6 +6,7 @@
 package io.opentelemetry.api.metrics;
 
 import io.opentelemetry.api.OpenTelemetry;
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 
 /**
@@ -43,5 +44,5 @@ static MeterProvider getDefault() {
    * @param instrumentationVersion The version of the instrumentation library.
    * @return a tracer instance.
    */
-  Meter get(String instrumentationName, String instrumentationVersion);
+  Meter get(String instrumentationName, @Nullable String instrumentationVersion);
 }
diff --git a/api/src/main/java/io/opentelemetry/api/trace/DefaultTracerProvider.java b/api/src/main/java/io/opentelemetry/api/trace/DefaultTracerProvider.java
index 7cb4219efc8..88ac1b216c8 100644
--- a/api/src/main/java/io/opentelemetry/api/trace/DefaultTracerProvider.java
+++ b/api/src/main/java/io/opentelemetry/api/trace/DefaultTracerProvider.java
@@ -5,6 +5,7 @@
 
 package io.opentelemetry.api.trace;
 
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 
 @ThreadSafe
@@ -22,7 +23,7 @@ public Tracer get(String instrumentationName) {
   }
 
   @Override
-  public Tracer get(String instrumentationName, String instrumentationVersion) {
+  public Tracer get(String instrumentationName, @Nullable String instrumentationVersion) {
     return Tracer.getDefault();
   }
 
diff --git a/api/src/main/java/io/opentelemetry/api/trace/TracerProvider.java b/api/src/main/java/io/opentelemetry/api/trace/TracerProvider.java
index 67bd240c6b7..c2eec22944d 100644
--- a/api/src/main/java/io/opentelemetry/api/trace/TracerProvider.java
+++ b/api/src/main/java/io/opentelemetry/api/trace/TracerProvider.java
@@ -7,6 +7,7 @@
 
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.api.trace.spi.TracerProviderFactory;
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 
 /**
@@ -45,5 +46,5 @@ static TracerProvider getDefault() {
    *     "semver:1.0.0").
    * @return a tracer instance.
    */
-  Tracer get(String instrumentationName, String instrumentationVersion);
+  Tracer get(String instrumentationName, @Nullable String instrumentationVersion);
 }
diff --git a/api/src/test/java/io/opentelemetry/api/OpenTelemetryTest.java b/api/src/test/java/io/opentelemetry/api/OpenTelemetryTest.java
index 94986824b31..ba1e7ad6629 100644
--- a/api/src/test/java/io/opentelemetry/api/OpenTelemetryTest.java
+++ b/api/src/test/java/io/opentelemetry/api/OpenTelemetryTest.java
@@ -206,7 +206,7 @@ public Tracer get(String instrumentationName) {
     }
 
     @Override
-    public Tracer get(String instrumentationName, String instrumentationVersion) {
+    public Tracer get(String instrumentationName, @Nullable String instrumentationVersion) {
       return get(instrumentationName);
     }
 
@@ -230,7 +230,7 @@ public Meter get(String instrumentationName) {
     }
 
     @Override
-    public Meter get(String instrumentationName, String instrumentationVersion) {
+    public Meter get(String instrumentationName, @Nullable String instrumentationVersion) {
       return get(instrumentationName);
     }
 
@@ -332,7 +332,7 @@ public Meter get(String instrumentationName) {
     }
 
     @Override
-    public Meter get(String instrumentationName, String instrumentationVersion) {
+    public Meter get(String instrumentationName, @Nullable String instrumentationVersion) {
       return get(instrumentationName);
     }
   }
diff --git a/sdk/all/src/main/java/io/opentelemetry/sdk/OpenTelemetrySdk.java b/sdk/all/src/main/java/io/opentelemetry/sdk/OpenTelemetrySdk.java
index 14e7d4430af..50fc91a8247 100644
--- a/sdk/all/src/main/java/io/opentelemetry/sdk/OpenTelemetrySdk.java
+++ b/sdk/all/src/main/java/io/opentelemetry/sdk/OpenTelemetrySdk.java
@@ -299,7 +299,7 @@ public Tracer get(String instrumentationName) {
     }
 
     @Override
-    public Tracer get(String instrumentationName, String instrumentationVersion) {
+    public Tracer get(String instrumentationName, @Nullable String instrumentationVersion) {
       return delegate.get(instrumentationName, instrumentationVersion);
     }