Fixed the error when using optional() and anyOf() together

fixes gh-1215

spring-cloud-contract-spec/src/main/groovy/org/springframework/cloud/contract/spec/internal/OptionalProperty.groovy

@@ -45,8 +45,16 @@ class OptionalProperty implements Serializable, CanBeDynamic {
 	}
 
 	String value() {
-		return this.value instanceof RegexProperty ?
-				((RegexProperty) this.value).pattern.pattern() : this.value
+		Object valueToCheck = valueToCheck()
+		return (valueToCheck instanceof RegexProperty || valueToCheck instanceof Pattern) ?
+				new RegexProperty(valueToCheck).pattern.pattern() : valueToCheck
+	}
+
+	private Object valueToCheck() {
+		if (this.value instanceof ClientDslProperty) {
+			return ((ClientDslProperty) this.value).getClientValue()
+		}
+		return this.value
 	}
 
 	protected Pattern optionalPatternValue() {

spring-cloud-contract-spec/src/test/groovy/org/springframework/cloud/contract/spec/internal/ContractSpec.groovy

@@ -442,4 +442,23 @@ then:
 		then:
 			thrown(AssertionError)
 	}
+
+	@Issue("1215")
+	def 'should work fine when dealing with anyOf'() {
+		when:
+			Contract.make {
+				request {
+					method 'GET'
+					url '/any'
+					body (
+							foo: $(consumer(optional(anyOf('WORKS','MIGHTY', 'DESPAIR'))), producer('DESPAIR'))
+					)
+				}
+				response {
+					status OK()
+				}
+			}
+		then:
+			noExceptionThrown()
+	}
 }