Don't fail build on merge failure

Be more lenient when processing additional metadata json files.

Fixes spring-projectsgh-2287
Closes spring-projectsgh-2288

spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/ConfigurationMetadataAnnotationProcessor.java

@@ -16,7 +16,6 @@
 
 package org.springframework.boot.configurationprocessor;
 
-import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.util.Collections;
@@ -107,10 +106,6 @@ public synchronized void init(ProcessingEnvironment env) {
 		}
 	}
 
-	private void logWarning(String msg) {
-		this.processingEnv.getMessager().printMessage(Kind.WARNING, msg);
-	}
-
 	@Override
 	public boolean process(Set<? extends TypeElement> annotations,
 			RoundEnvironment roundEnv) {
@@ -361,9 +356,14 @@ private ConfigurationMetadata mergeManualMetadata(ConfigurationMetadata metadata
 				inputStream.close();
 			}
 		}
-		catch (IOException ex) {
+		catch (Exception ex) {
+			logWarning("Unable to merge additional-spring-configuration-metadata.json");
 			return metadata;
 		}
 	}
 
+	private void logWarning(String msg) {
+		this.processingEnv.getMessager().printMessage(Kind.WARNING, msg);
+	}
+
 }