RelaxedConversionService support lowercase enums

Update RelaxedConversionService to support enums that are themselves
declared as lower-case (or mixed case) items.

Fixes gh-996

spring-boot/src/main/java/org/springframework/boot/bind/RelaxedConversionService.java

@@ -16,6 +16,9 @@
 
 package org.springframework.boot.bind;
 
+import java.util.EnumSet;
+import java.util.Set;
+
 import org.springframework.core.convert.ConversionFailedException;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.TypeDescriptor;
@@ -117,7 +120,14 @@ class RelaxedConversionService implements ConversionService {
 					// It's an empty enum identifier: reset the enum value to null.
 					return null;
 				}
-				return (T) Enum.valueOf(this.enumType, source.trim().toUpperCase());
+				source = source.trim();
+				for (T candidate : (Set<T>) EnumSet.allOf(this.enumType)) {
+					if (candidate.name().equalsIgnoreCase(source)) {
+						return candidate;
+					}
+				}
+				throw new IllegalArgumentException("No enum constant "
+						+ this.enumType.getCanonicalName() + "." + source);
 			}
 		}
 

spring-boot/src/test/java/org/springframework/boot/bind/RelaxedDataBinderTests.java

@@ -442,7 +442,7 @@ public class RelaxedDataBinderTests {
 
 		result = bind(target, "bingo: oR");
 		assertThat(result.getErrorCount(), equalTo(0));
-		assertThat(target.getBingo(), equalTo(Bingo.OR));
+		assertThat(target.getBingo(), equalTo(Bingo.or));
 
 		result = bind(target, "bingo: that");
 		assertThat(result.getErrorCount(), equalTo(0));
@@ -755,7 +755,7 @@ public class RelaxedDataBinderTests {
 	}
 
 	static enum Bingo {
-		THIS, OR, THAT
+		THIS, or, THAT
 	}
 
 	public static class ValidatedTarget {