diff --git a/org.hl7.fhir.dstu2/src/test/java/org/hl7/fhir/dstu2/model/BaseDateTimeTypeTests.java b/org.hl7.fhir.dstu2/src/test/java/org/hl7/fhir/dstu2/model/BaseDateTimeTypeTests.java
new file mode 100644
index 000000000..9ca552247
--- /dev/null
+++ b/org.hl7.fhir.dstu2/src/test/java/org/hl7/fhir/dstu2/model/BaseDateTimeTypeTests.java
@@ -0,0 +1,63 @@
+package org.hl7.fhir.dstu2.model;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.lang.reflect.InvocationTargetException;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class BaseDateTimeTypeTests {
+  
+  private static Stream<Arguments> getInvalidStringParams() {
+      return Stream.of(
+              Arguments.of(DateType.class, "1933-01-02T12:34:56"),
+              Arguments.of(DateType.class, "1933-01-02T12:34:56.7"),
+              Arguments.of(DateType.class, "1933-01-02T12:34:56.78"),
+              Arguments.of(DateType.class, "1933-01-02T12:34:56.789"),
+              Arguments.of(InstantType.class, "1933"),
+              Arguments.of(InstantType.class, "1933-01"),
+              Arguments.of(InstantType.class, "1933-01-02")
+      );
+  }
+
+  @ParameterizedTest
+  @MethodSource("getInvalidStringParams")
+  public <K extends BaseDateTimeType> void testInvalidString(Class<K> clazz, String param) throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+    InvocationTargetException exceptionWrapper =  Assertions.assertThrows(InvocationTargetException.class, () ->  clazz.getConstructor(String.class).newInstance(param));
+    assertEquals(IllegalArgumentException.class, exceptionWrapper.getTargetException().getClass());
+     K srcInstance = clazz.getDeclaredConstructor().newInstance();
+     Assertions.assertThrows(IllegalArgumentException.class, () -> srcInstance.setValueAsString(param));
+  }
+
+  private static Stream<Arguments> getValidStringParams() {
+      return Stream.of(
+        Arguments.of(DateType.class, "1933"),
+        Arguments.of(DateType.class, "1933-01"),
+        Arguments.of(DateType.class, "1933-01-02"),
+        Arguments.of(DateTimeType.class, "1933"),
+        Arguments.of(DateTimeType.class, "1933-01"),
+        Arguments.of(DateTimeType.class, "1933-01-02"),
+        Arguments.of(DateTimeType.class, "1933-01-02T12:34:56"),
+        Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.7"),
+        Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.78"),
+        Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.789"),
+        Arguments.of(InstantType.class, "1933-01-02T12:34:56"),
+        Arguments.of(InstantType.class, "1933-01-02T12:34:56.7"),
+        Arguments.of(InstantType.class, "1933-01-02T12:34:56.78"),
+        Arguments.of(InstantType.class, "1933-01-02T12:34:56.789")
+      );
+  }
+
+  @ParameterizedTest
+  @MethodSource("getValidStringParams")
+  public <K extends BaseDateTimeType> void testValidString(Class<K> clazz, String param) throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+    clazz.getConstructor(String.class).newInstance(param);
+    K srcInstance = clazz.getDeclaredConstructor().newInstance();
+    srcInstance.setValueAsString(param);
+    assertEquals(param, srcInstance.getValueAsString());
+  }
+}
diff --git a/org.hl7.fhir.dstu2016may/src/test/java/org/hl7/fhir/dstu2016may/model/BaseDateTimeTypeTests.java b/org.hl7.fhir.dstu2016may/src/test/java/org/hl7/fhir/dstu2016may/model/BaseDateTimeTypeTests.java
new file mode 100644
index 000000000..a51326362
--- /dev/null
+++ b/org.hl7.fhir.dstu2016may/src/test/java/org/hl7/fhir/dstu2016may/model/BaseDateTimeTypeTests.java
@@ -0,0 +1,64 @@
+package org.hl7.fhir.dstu2016may.model;
+
+import ca.uhn.fhir.parser.DataFormatException;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.lang.reflect.InvocationTargetException;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class BaseDateTimeTypeTests {
+  
+  private static Stream<Arguments> getInvalidStringParams() {
+      return Stream.of(
+              Arguments.of(DateType.class, "1933-01-02T12:34:56"),
+              Arguments.of(DateType.class, "1933-01-02T12:34:56.7"),
+              Arguments.of(DateType.class, "1933-01-02T12:34:56.78"),
+              Arguments.of(DateType.class, "1933-01-02T12:34:56.789"),
+              Arguments.of(InstantType.class, "1933"),
+              Arguments.of(InstantType.class, "1933-01"),
+              Arguments.of(InstantType.class, "1933-01-02")
+      );
+  }
+
+  @ParameterizedTest
+  @MethodSource("getInvalidStringParams")
+  public <K extends BaseDateTimeType> void testInvalidString(Class<K> clazz, String param) throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+    InvocationTargetException exceptionWrapper =  Assertions.assertThrows(InvocationTargetException.class, () ->  clazz.getConstructor(String.class).newInstance(param));
+    assertEquals(DataFormatException.class, exceptionWrapper.getTargetException().getClass());
+     K srcInstance = clazz.getDeclaredConstructor().newInstance();
+     Assertions.assertThrows(DataFormatException.class, () -> srcInstance.setValueAsString(param));
+  }
+
+  private static Stream<Arguments> getValidStringParams() {
+      return Stream.of(
+        Arguments.of(DateType.class, "1933"),
+        Arguments.of(DateType.class, "1933-01"),
+        Arguments.of(DateType.class, "1933-01-02"),
+        Arguments.of(DateTimeType.class, "1933"),
+        Arguments.of(DateTimeType.class, "1933-01"),
+        Arguments.of(DateTimeType.class, "1933-01-02"),
+        Arguments.of(DateTimeType.class, "1933-01-02T12:34:56"),
+        Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.7"),
+        Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.78"),
+        Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.789"),
+        Arguments.of(InstantType.class, "1933-01-02T12:34:56"),
+        Arguments.of(InstantType.class, "1933-01-02T12:34:56.7"),
+        Arguments.of(InstantType.class, "1933-01-02T12:34:56.78"),
+        Arguments.of(InstantType.class, "1933-01-02T12:34:56.789")
+      );
+  }
+
+  @ParameterizedTest
+  @MethodSource("getValidStringParams")
+  public <K extends BaseDateTimeType> void testValidString(Class<K> clazz, String param) throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+    clazz.getConstructor(String.class).newInstance(param);
+    K srcInstance = clazz.getDeclaredConstructor().newInstance();
+    srcInstance.setValueAsString(param);
+    assertEquals(param, srcInstance.getValueAsString());
+  }
+}
diff --git a/org.hl7.fhir.dstu3/src/test/java/org/hl7/fhir/dstu3/model/BaseDateTimeTypeTests.java b/org.hl7.fhir.dstu3/src/test/java/org/hl7/fhir/dstu3/model/BaseDateTimeTypeTests.java
new file mode 100644
index 000000000..3d10288d8
--- /dev/null
+++ b/org.hl7.fhir.dstu3/src/test/java/org/hl7/fhir/dstu3/model/BaseDateTimeTypeTests.java
@@ -0,0 +1,64 @@
+package org.hl7.fhir.dstu3.model;
+
+import ca.uhn.fhir.parser.DataFormatException;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.lang.reflect.InvocationTargetException;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class BaseDateTimeTypeTests {
+  
+  private static Stream<Arguments> getInvalidStringParams() {
+      return Stream.of(
+              Arguments.of(DateType.class, "1933-01-02T12:34:56"),
+              Arguments.of(DateType.class, "1933-01-02T12:34:56.7"),
+              Arguments.of(DateType.class, "1933-01-02T12:34:56.78"),
+              Arguments.of(DateType.class, "1933-01-02T12:34:56.789"),
+              Arguments.of(InstantType.class, "1933"),
+              Arguments.of(InstantType.class, "1933-01"),
+              Arguments.of(InstantType.class, "1933-01-02")
+      );
+  }
+
+  @ParameterizedTest
+  @MethodSource("getInvalidStringParams")
+  public <K extends BaseDateTimeType> void testInvalidString(Class<K> clazz, String param) throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+    InvocationTargetException exceptionWrapper =  Assertions.assertThrows(InvocationTargetException.class, () ->  clazz.getConstructor(String.class).newInstance(param));
+    assertEquals(DataFormatException.class, exceptionWrapper.getTargetException().getClass());
+     K srcInstance = clazz.getDeclaredConstructor().newInstance();
+     Assertions.assertThrows(DataFormatException.class, () -> srcInstance.setValueAsString(param));
+  }
+
+  private static Stream<Arguments> getValidStringParams() {
+      return Stream.of(
+        Arguments.of(DateType.class, "1933"),
+        Arguments.of(DateType.class, "1933-01"),
+        Arguments.of(DateType.class, "1933-01-02"),
+        Arguments.of(DateTimeType.class, "1933"),
+        Arguments.of(DateTimeType.class, "1933-01"),
+        Arguments.of(DateTimeType.class, "1933-01-02"),
+        Arguments.of(DateTimeType.class, "1933-01-02T12:34:56"),
+        Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.7"),
+        Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.78"),
+        Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.789"),
+        Arguments.of(InstantType.class, "1933-01-02T12:34:56"),
+        Arguments.of(InstantType.class, "1933-01-02T12:34:56.7"),
+        Arguments.of(InstantType.class, "1933-01-02T12:34:56.78"),
+        Arguments.of(InstantType.class, "1933-01-02T12:34:56.789")
+      );
+  }
+
+  @ParameterizedTest
+  @MethodSource("getValidStringParams")
+  public <K extends BaseDateTimeType> void testValidString(Class<K> clazz, String param) throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+    clazz.getConstructor(String.class).newInstance(param);
+    K srcInstance = clazz.getDeclaredConstructor().newInstance();
+    srcInstance.setValueAsString(param);
+    assertEquals(param, srcInstance.getValueAsString());
+  }
+}
diff --git a/org.hl7.fhir.r4/src/test/java/org/hl7/fhir/r4/model/BaseDateTimeTypeTest.java b/org.hl7.fhir.r4/src/test/java/org/hl7/fhir/r4/model/BaseDateTimeTypeTest.java
index af866441c..c4141d77c 100644
--- a/org.hl7.fhir.r4/src/test/java/org/hl7/fhir/r4/model/BaseDateTimeTypeTest.java
+++ b/org.hl7.fhir.r4/src/test/java/org/hl7/fhir/r4/model/BaseDateTimeTypeTest.java
@@ -1,8 +1,17 @@
 package org.hl7.fhir.r4.model;
 
+import ca.uhn.fhir.parser.DataFormatException;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.lang.reflect.InvocationTargetException;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class BaseDateTimeTypeTest {
 
@@ -70,4 +79,53 @@ public class BaseDateTimeTypeTest {
     return leftDt.equalsUsingFhirPathRules(rightDt);
   }
 
+  private static Stream<Arguments> getInvalidStringParams() {
+    return Stream.of(
+      Arguments.of(DateType.class, "1933-01-02T12:34:56"),
+      Arguments.of(DateType.class, "1933-01-02T12:34:56.7"),
+      Arguments.of(DateType.class, "1933-01-02T12:34:56.78"),
+      Arguments.of(DateType.class, "1933-01-02T12:34:56.789"),
+      Arguments.of(InstantType.class, "1933"),
+      Arguments.of(InstantType.class, "1933-01"),
+      Arguments.of(InstantType.class, "1933-01-02")
+    );
+  }
+
+  @ParameterizedTest
+  @MethodSource("getInvalidStringParams")
+  public <K extends BaseDateTimeType> void testInvalidString(Class<K> clazz, String param) throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+    InvocationTargetException exceptionWrapper =  Assertions.assertThrows(InvocationTargetException.class, () ->  clazz.getConstructor(String.class).newInstance(param));
+    assertEquals(IllegalArgumentException.class, exceptionWrapper.getTargetException().getClass());
+    K srcInstance = clazz.getDeclaredConstructor().newInstance();
+    Assertions.assertThrows(IllegalArgumentException.class, () -> srcInstance.setValueAsString(param));
+  }
+
+  private static Stream<Arguments> getValidStringParams() {
+    return Stream.of(
+      Arguments.of(DateType.class, "1933"),
+      Arguments.of(DateType.class, "1933-01"),
+      Arguments.of(DateType.class, "1933-01-02"),
+      Arguments.of(DateTimeType.class, "1933"),
+      Arguments.of(DateTimeType.class, "1933-01"),
+      Arguments.of(DateTimeType.class, "1933-01-02"),
+      Arguments.of(DateTimeType.class, "1933-01-02T12:34:56"),
+      Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.7"),
+      Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.78"),
+      Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.789"),
+      Arguments.of(InstantType.class, "1933-01-02T12:34:56"),
+      Arguments.of(InstantType.class, "1933-01-02T12:34:56.7"),
+      Arguments.of(InstantType.class, "1933-01-02T12:34:56.78"),
+      Arguments.of(InstantType.class, "1933-01-02T12:34:56.789")
+    );
+  }
+
+  @ParameterizedTest
+  @MethodSource("getValidStringParams")
+  public <K extends BaseDateTimeType> void testValidString(Class<K> clazz, String param) throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+    clazz.getConstructor(String.class).newInstance(param);
+    K srcInstance = clazz.getDeclaredConstructor().newInstance();
+    srcInstance.setValueAsString(param);
+    assertEquals(param, srcInstance.getValueAsString());
+  }
+
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.r4b/src/test/java/org/hl7/fhir/r4b/model/BaseDateTimeTypeTest.java b/org.hl7.fhir.r4b/src/test/java/org/hl7/fhir/r4b/model/BaseDateTimeTypeTest.java
index 2fa22b0b2..62b5fd34c 100644
--- a/org.hl7.fhir.r4b/src/test/java/org/hl7/fhir/r4b/model/BaseDateTimeTypeTest.java
+++ b/org.hl7.fhir.r4b/src/test/java/org/hl7/fhir/r4b/model/BaseDateTimeTypeTest.java
@@ -1,9 +1,16 @@
 package org.hl7.fhir.r4b.model;
 
+import java.lang.reflect.InvocationTargetException;
 import java.util.TimeZone;
+import java.util.stream.Stream;
 
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class BaseDateTimeTypeTest {
 
@@ -104,4 +111,53 @@ public class BaseDateTimeTypeTest {
     return leftDt.equalsUsingFhirPathRules(rightDt);
   }
 
+  private static Stream<Arguments> getInvalidStringParams() {
+    return Stream.of(
+      Arguments.of(DateType.class, "1933-01-02T12:34:56"),
+      Arguments.of(DateType.class, "1933-01-02T12:34:56.7"),
+      Arguments.of(DateType.class, "1933-01-02T12:34:56.78"),
+      Arguments.of(DateType.class, "1933-01-02T12:34:56.789"),
+      Arguments.of(InstantType.class, "1933"),
+      Arguments.of(InstantType.class, "1933-01"),
+      Arguments.of(InstantType.class, "1933-01-02")
+    );
+  }
+
+  @ParameterizedTest
+  @MethodSource("getInvalidStringParams")
+  public <K extends BaseDateTimeType> void testInvalidString(Class<K> clazz, String param) throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+    InvocationTargetException exceptionWrapper =  Assertions.assertThrows(InvocationTargetException.class, () ->  clazz.getConstructor(String.class).newInstance(param));
+    assertEquals(IllegalArgumentException.class, exceptionWrapper.getTargetException().getClass());
+    K srcInstance = clazz.getDeclaredConstructor().newInstance();
+    Assertions.assertThrows(IllegalArgumentException.class, () -> srcInstance.setValueAsString(param));
+  }
+
+  private static Stream<Arguments> getValidStringParams() {
+    return Stream.of(
+      Arguments.of(DateType.class, "1933"),
+      Arguments.of(DateType.class, "1933-01"),
+      Arguments.of(DateType.class, "1933-01-02"),
+      Arguments.of(DateTimeType.class, "1933"),
+      Arguments.of(DateTimeType.class, "1933-01"),
+      Arguments.of(DateTimeType.class, "1933-01-02"),
+      Arguments.of(DateTimeType.class, "1933-01-02T12:34:56"),
+      Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.7"),
+      Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.78"),
+      Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.789"),
+      Arguments.of(InstantType.class, "1933-01-02T12:34:56"),
+      Arguments.of(InstantType.class, "1933-01-02T12:34:56.7"),
+      Arguments.of(InstantType.class, "1933-01-02T12:34:56.78"),
+      Arguments.of(InstantType.class, "1933-01-02T12:34:56.789")
+    );
+  }
+
+  @ParameterizedTest
+  @MethodSource("getValidStringParams")
+  public <K extends BaseDateTimeType> void testValidString(Class<K> clazz, String param) throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+    clazz.getConstructor(String.class).newInstance(param);
+    K srcInstance = clazz.getDeclaredConstructor().newInstance();
+    srcInstance.setValueAsString(param);
+    assertEquals(param, srcInstance.getValueAsString());
+  }
+
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/BaseDateTimeType.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/BaseDateTimeType.java
index 5c41bca31..b35f933fe 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/BaseDateTimeType.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/BaseDateTimeType.java
@@ -100,9 +100,6 @@ public abstract class BaseDateTimeType extends PrimitiveType<Date> {
 	 */
 	public BaseDateTimeType(String theString) {
 		setValueAsString(theString);
-		if (isPrecisionAllowed(getPrecision()) == false) {
-			throw new IllegalArgumentException("Invalid date/time string (datatype " + getClass().getSimpleName() + " does not support " + getPrecision() + " precision): " + theString);
-		}
 	}
 
 	/**
diff --git a/org.hl7.fhir.r5/src/test/java/org/hl7/fhir/r5/model/BaseDateTimeTypeTest.java b/org.hl7.fhir.r5/src/test/java/org/hl7/fhir/r5/model/BaseDateTimeTypeTest.java
index 929a86cbd..6f2464a5e 100644
--- a/org.hl7.fhir.r5/src/test/java/org/hl7/fhir/r5/model/BaseDateTimeTypeTest.java
+++ b/org.hl7.fhir.r5/src/test/java/org/hl7/fhir/r5/model/BaseDateTimeTypeTest.java
@@ -1,9 +1,16 @@
 package org.hl7.fhir.r5.model;
 
+import java.lang.reflect.InvocationTargetException;
 import java.util.TimeZone;
+import java.util.stream.Stream;
 
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class BaseDateTimeTypeTest {
 
@@ -104,4 +111,53 @@ public class BaseDateTimeTypeTest {
     return leftDt.equalsUsingFhirPathRules(rightDt);
   }
 
+  private static Stream<Arguments> getInvalidStringParams() {
+    return Stream.of(
+      Arguments.of(DateType.class, "1933-01-02T12:34:56"),
+      Arguments.of(DateType.class, "1933-01-02T12:34:56.7"),
+      Arguments.of(DateType.class, "1933-01-02T12:34:56.78"),
+      Arguments.of(DateType.class, "1933-01-02T12:34:56.789"),
+      Arguments.of(InstantType.class, "1933"),
+      Arguments.of(InstantType.class, "1933-01"),
+      Arguments.of(InstantType.class, "1933-01-02")
+    );
+  }
+
+  @ParameterizedTest
+  @MethodSource("getInvalidStringParams")
+  public <K extends BaseDateTimeType> void testInvalidString(Class<K> clazz, String param) throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+    InvocationTargetException exceptionWrapper =  Assertions.assertThrows(InvocationTargetException.class, () ->  clazz.getConstructor(String.class).newInstance(param));
+    assertEquals(IllegalArgumentException.class, exceptionWrapper.getTargetException().getClass());
+    K srcInstance = clazz.getDeclaredConstructor().newInstance();
+    Assertions.assertThrows(IllegalArgumentException.class, () -> srcInstance.setValueAsString(param));
+  }
+
+  private static Stream<Arguments> getValidStringParams() {
+    return Stream.of(
+      Arguments.of(DateType.class, "1933"),
+      Arguments.of(DateType.class, "1933-01"),
+      Arguments.of(DateType.class, "1933-01-02"),
+      Arguments.of(DateTimeType.class, "1933"),
+      Arguments.of(DateTimeType.class, "1933-01"),
+      Arguments.of(DateTimeType.class, "1933-01-02"),
+      Arguments.of(DateTimeType.class, "1933-01-02T12:34:56"),
+      Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.7"),
+      Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.78"),
+      Arguments.of(DateTimeType.class, "1933-01-02T12:34:56.789"),
+      Arguments.of(InstantType.class, "1933-01-02T12:34:56"),
+      Arguments.of(InstantType.class, "1933-01-02T12:34:56.7"),
+      Arguments.of(InstantType.class, "1933-01-02T12:34:56.78"),
+      Arguments.of(InstantType.class, "1933-01-02T12:34:56.789")
+    );
+  }
+
+  @ParameterizedTest
+  @MethodSource("getValidStringParams")
+  public <K extends BaseDateTimeType> void testValidString(Class<K> clazz, String param) throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+    clazz.getConstructor(String.class).newInstance(param);
+    K srcInstance = clazz.getDeclaredConstructor().newInstance();
+    srcInstance.setValueAsString(param);
+    assertEquals(param, srcInstance.getValueAsString());
+  }
+
 }
\ No newline at end of file