Breaking test and fix

org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/DecimalType.java

@@ -35,6 +35,7 @@ import java.math.BigDecimal;
 import java.math.MathContext;
 import java.math.RoundingMode;
 
+import org.apache.commons.lang3.StringUtils;
 import org.hl7.fhir.instance.model.api.IBaseDecimalDatatype;
 
 import ca.uhn.fhir.model.api.annotation.DatatypeDef;
@@ -166,8 +167,13 @@ public class DecimalType extends PrimitiveType<BigDecimal> implements Comparable
 	}
 
   public void setValueAsString(String theString) {
-    setValue(new BigDecimal(theString));
-    setRepresentation(theString);
+    if (StringUtils.isBlank(theString)) {
+      setValue((BigDecimal) null);
+      setRepresentation(null);
+    } else {
+      setValue(new BigDecimal(theString));
+      setRepresentation(theString);
+    }
   }
 
 	@Override
@@ -184,7 +190,7 @@ public class DecimalType extends PrimitiveType<BigDecimal> implements Comparable
 	/**
 	 * A parser can provide a literal representation for the decimal value that preserves
 	 * the presented form.
-	 * 
+	 * <p/>
 	 * All sorts of bad things can happen if this method is used to set the string representation
 	 * to anything other than what was parsed into the actual value. Don't do that
 	 * 

org.hl7.fhir.r5/src/test/java/org/hl7/fhir/r5/model/DecimalTypeNullTest.java

@@ -3,9 +3,23 @@ package org.hl7.fhir.r5.model;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.DisplayName;
 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.util.List;
+import java.util.stream.Stream;
 
 class DecimalTypeNullTest {
 
+  public static Stream<Arguments> provideEmptyOrNullStringsConstructor() {
+    return Stream.of(
+      Arguments.of((String)null),
+      Arguments.of(""),
+      Arguments.of("  ")
+    );
+  }
+
   @Test
   @DisplayName("Test null value toString()")
   void testToString() {
@@ -44,4 +58,19 @@ class DecimalTypeNullTest {
     DecimalType copyDecimal = (DecimalType) nullDecimal.typedCopy();
     Assertions.assertNull(copyDecimal.getValue());
   }
+
+  @ParameterizedTest
+  @MethodSource("provideEmptyOrNullStringsConstructor")
+  void testNullValue(String theStringValue) {
+    DecimalType nullDecimal = new DecimalType();
+    Assertions.assertNull(nullDecimal.getValue());
+    Assertions.assertNull(nullDecimal.asStringValue());
+
+    DecimalType anotherNullDecimal = new DecimalType(theStringValue);
+    Assertions.assertNull(anotherNullDecimal.getValue());
+    Assertions.assertNull(anotherNullDecimal.asStringValue());
+
+    Assertions.assertTrue(nullDecimal.equalsDeep(anotherNullDecimal));
+    Assertions.assertTrue(nullDecimal.equalsShallow(anotherNullDecimal));
+  }
 }